Olight makes the lights used as examples here. Olight specs and regular prices come from its US product pages and user manuals as of September 2026. Definitions quote or follow the standards bodies named in each entry; worked numbers are calculations from published figures, not lab measurements.
⚡ TL;DR
Flashlight terms are the words on a spec sheet that tell you how much light a flashlight makes (lumens), how far it reaches (candela and beam distance), how long it runs (runtime and watt-hours) and how much abuse it takes (IP code and impact rating). This glossary defines 60 of them in one sentence each, grouped by category, with an Olight spec as the example.
A single Olight product page can stack six unfamiliar words in one spec table: TIR optic lens, 7,225 candela, IPX8, MCC, 16340, Moon 0.5 lumens. The definitions are scattered across standards, manuals and forum posts. Here every term gets one sentence, a real number and the rule behind it.
This table shows the five flashlight terms that answer the five questions most buyers ask first.
| Buyer question | Term to read | Unit | Olight example |
|---|---|---|---|
| How bright? | Lumens, peak and after step-down | lm | Baton 4: 1,300~600~300 lumens |
| How far? | Peak beam intensity and beam distance | cd, m | Warrior X 4: 99,310 cd, 630 m |
| How long? | Runtime for a named mode | h, min | Perun 3: Med 120 lumens, 25 hours |
| How wet? | IP code | IPX8, IP68, IP66 | Oclip 2 Pro: IP66 |
| What color? | CCT and CRI | K, CRI value | Perun 3 Mini HCRI: 4,000K to 5,000K, CRI 90 |
📋 Table of Contents
- 1. Quick Answer: Which Flashlight Terms Should You Learn First?
- 2. Optical Terms: Light Output, Beam and Color
- 3. Battery and Power Terms
- 4. Body, Material and Structure Terms
- 5. Switch and Mode Terms
- 6. Standards and Certification Terms
- 7. Carry and Form Terms
- 8. What Are the Parts of a Flashlight Called?
- 9. What Are Some Common Lighting Terms?
- 10. What Are Some Words Related to Flashlight?
- 11. Five Terms to Read First, by Scenario
- 12. Flashlight Glossary Mix-ups: Term Pairs People Confuse
- 13. Three Worked Numbers That Tie the Terms Together
- 14. Your Flashlight Terms Checklist
- 15. FAQ
Quick Answer: Which Flashlight Terms Should You Learn First?
Learn six flashlight terms first: lumens, candela, beam distance, runtime, IP code and battery type. They come from the ANSI/PLATO FL 1 standard, the IEC 60529 IP system and the battery label, and together they answer brightness, reach, endurance, water resistance and refueling. The other 54 terms explain how a light gets those numbers and how you operate it.
Read lumens with runtime, because high outputs step down within minutes.
Olight's full range of flashlights prints all six on every product page.
Optical Terms: Light Output, Beam and Color
Optical flashlight terms describe how much light comes out, how it is shaped and what color it is. The base units come from the SI as NIST publishes it, the beam figures from ANSI/PLATO FL 1, and the color terms from the CIE vocabulary and the U.S. Department of Energy.
NIST's SI guide (SP 330, 2019 edition) sets the three units, and notes that "Lumen and lux are derived from the base unit candela."
Lumen
A lumen (lm) is the SI unit of luminous flux, the total visible light a source emits in all directions, and NIST defines it as a candela times a steradian (lm = cd sr); the Olight Baton 4 is rated at 1,300 lumens.
Candela
NIST states that "The candela, symbol cd, is the SI unit of luminous intensity in a given direction," and the Olight Warrior X 4 tactical flashlight ($129.99, regular price, September 2026) packs 99,310 cd into a beam from 2,600 lumens, though at 249 g it is a duty light, not a pocket light.
Lux
A lux (lx) is one lumen per square meter of the lit surface (NIST lists lx = lm/m²), so it measures the light that lands on your target, and on the beam's axis it equals candela divided by the distance in meters squared.
Peak Beam Intensity
Peak beam intensity is the FL 1 name for the candela figure; Streamlight's FL1 summary, written before the 2025 edition, calls it "The maximum luminous intensity typically along the central axis of a cone of light," and the Seeker 4 Pro lists 16,895 candela.
Beam Distance
Beam distance is "The distance from the device at which the light beam is 0.25 lux," per the same FL1 summary, so the Warrior X 4's 630 m rating marks where its beam fades to that faint level.
Throw
Throw is Olight's everyday word for reach, as in the Baton 4 page's "170m throw" and the Oclip 2 Pro's "Max Throw" of 125 m.
Flood
Flood describes a wide, even beam built for close work, and Olight uses it as a mode name: the Oclip 2 Pro's floodlight reaches 530 lumens.
Spotlight
Spotlight is Olight's mode name for a narrow beam on lights with two optics; on the Oclip 2 Pro, the spotlight gives 400 lumens and carries the 125 m reach.
Hotspot
The hotspot is the bright center of the beam, where FL 1 takes its peak beam intensity reading, a figure the Streamlight summary says "measures the brightest part of the beam."
TIR Optic
A TIR (total internal reflection) optic is a molded clear lens that bends and reflects light inside itself to shape the beam; Olight lists a "TIR Optic Lens" on the Baton 4, Warrior 3S and Seeker 4 Pro.
Aspheric Lens
An aspheric lens is a converging lens with a non-spherical surface that focuses light into a tight spot, and Olight pairs one with a TIR lens on the Marauder 3 to reach 250,000 candela.
LED
An LED is a semiconductor light source, and the DOE's LED basics page explains that LEDs "emit nearly monochromatic light," so white flashlight LEDs typically use "Phosphor conversion, in which a phosphor is used on or near the LED to convert the colored light to white light."
CCT
Correlated color temperature (CCT) is, in the CIE's CCT definition (CIE S 017:2020), the "temperature of a Planckian radiator having the chromaticity nearest the chromaticity associated with the given spectral distribution," given in kelvin; the Warrior X 4 lists 5,700K to 6,700K.
Cool White and Neutral White
Cool white (CW) and neutral white (NW) are Olight's labels for two CCT bands: the Perun 3 Mini CW is listed at 5,700K to 6,700K and the HCRI NW version at 4,000K to 5,000K.
CRI
The color rendering index (CRI) scores how faithfully a light shows object colors, and the DOE notes that "CRI of 90 or higher indicates excellent color fidelity," a line the HCRI version of the Olight Perun 3 Mini headlamp ($64.99, regular price, September 2026) clears at CRI 90 and the CW version (CRI 70) does not.
For the math that links these units, see our guides to beam distance and flashlight throw vs flood.
Battery and Power Terms
Battery flashlight terms tell you what stores the energy, how much it holds and how it gets refilled. Capacity (mAh) and energy (Wh) answer different questions, cell codes such as 16340 or 21700 decide whether a spare fits, and Olight adds its own words, such as MCC.
mAh
Milliamp-hours (mAh) measure charge capacity, not energy, so mAh compares two cells fairly only when their voltages match; the Baton 4's cell is 650 mAh at 3.6V.
Watt-hour
A watt-hour (Wh) measures stored energy, and the FAA's lithium battery guidance explains, "To calculate Wh, multiply the battery voltage by the Amp hours (Ah)," which is how the Baton 4 manual reaches "650mAh 3.6V (2.34Wh)."
Nominal Voltage
Nominal voltage is the reference voltage a maker uses to identify a cell and calculate its watt-hours, printed as 3.6V on the Baton 4's customized 16340 and 3.7V on the Marauder Mini 2's 32650 pack.
Cell Size Code
A cell size code such as 16340, 18650, 21700 or 32650 names the size of a cylindrical lithium-ion cell; a spare fits only when the maker lists that code as compatible.
Customized Battery
Customized battery is Olight's label for a cell built for one light, such as the "Customized 5000mAh 3.6V 21700" in the Warrior X 4, so buy replacements that match the listed part.
Li-ion and Li-polymer
Li-ion and Li-polymer name two packages of rechargeable lithium-ion cells, a rigid cylindrical can and a flat, flexible pouch; the Arkfeld Pro lists a "Built-in 1500mAh Lithium Polymer Battery."
Built-in Battery
A built-in battery is sealed inside the light and charged through a port, as on the i1R 2 Pro keychain light with its built-in 130 mAh 10220 cell.
AAA and 10440
AAA is a battery size usually filled by a 1.5V alkaline cell, and 10440 is a lithium-ion cell of similar size but higher voltage, so use one only where the maker lists it; the i3T 2 EOS ships with a 1.5V AAA alkaline and lists a 10440 as compatible.
MCC
MCC is Olight's magnetic charging cable, and not every version fits every light: the Warrior 3S manual says, "Only charge with standard MCC3, not compatible with other MCC."
Battery Level Indicator
A battery level indicator is a small light that reports charge, and the Baton 4 manual shows green in three steps (60% or more, 10% to 60%, 5% to 10%) and red below 5%.
For chemistry, capacity and storage in depth, see our guide to flashlight battery types.
Body, Material and Structure Terms
Structure terms name the physical parts of a flashlight and the materials and sensors that protect it. Most Olight bodies are aluminum alloy, some use Olight's own OAL alloy, and several manuals describe heat and proximity sensors that lower output on their own.
Bezel
The bezel is the ring at the front of the head that holds the lens in place, and Olight sells a replacement Warrior X / X Pro Black Bezel.
Tail Cap
The tail cap is the rear end of the body, often holding a switch, and the Warrior X 4 manual uses it to change settings: "unscrew the tail cap until the light goes out to switch to Tactical mode."
6061-T6 Aluminum
6061-T6 is a heat-treated aluminum alloy grade, listed by Olight as "A6061-T6 Aluminum Alloy" on the Marauder Mini 2 and Marauder 3.
OAL
OAL is Olight's name for its own alloy, listed as "OAL™ (Olight Proprietary Aluminum Alloy)" on the Seeker Ultra and as "O-Aluminum" on the Warrior Ultra.
Anodizing
Anodizing is an electrochemical process that grows a hard oxide layer on aluminum to resist wear and corrosion; our guide to aluminum flashlight material compares the types.
Impact Resistance
Impact resistance is "The degree to which a portable light resists damage when dropped on a solid surface," per the FL1 summary, and "Dropped samples must not exhibit any cracks or breaks and must remain fully functional"; the Oclip 2 Pro lists 2.0 m, while the Baton 4 manual lists 1.5 m.
Thermal Management
Thermal management is circuitry that cuts output to control heat, which the Arkfeld Pro warning manual describes as "The built-in thermister monitors the temperature of the light in real time and suppresses overheating by reducing the output."
Proximity Sensor
A proximity sensor dims the light when something blocks the lens; the Warrior 3S manual says that at level 3 or higher, "if the front lens proximity sensor detects an obstruction nearby, the brightness will automatically reduce."
Working Temperature
Working temperature is the ambient range the maker rates the light for, listed as 0 to 40 ℃ on the Marauder Mini 2; the Oclip 2 manual adds that "In environments below 0°C (32°F), the white light is limited to Low and Medium modes."
Switch and Mode Terms
Switch and mode terms describe how you turn a light on, how you move between brightness levels and how you stop it from turning on by accident. The same output handles very differently on a side switch, a tail switch or a rotary knob, and Olight manuals define each behavior in plain steps.
Side Switch
A side switch is a button on the body, and the Perun 3 page describes its large metal version as "concave to avoid unwanted activation during transit or storage."
Tail Switch
A tail switch is a button at the rear of the light, used as the only switch on the Warrior X 4 and the i3T 2 EOS.
Dual Switch
A dual switch pairs a side switch with a tail switch, as on the Warrior 3S, so you can run everyday modes from the side and momentary output from the tail.
Rotary Switch
A rotary switch sets brightness by turning, and the Seeker 4 Pro manual says, "Rotate clockwise, the memorized brightness level will increase steplessly."
Momentary-on
Momentary-on means the light stays lit only while you hold the switch, as in the Warrior X 4 manual: "Tap and hold to turn on and maintain Low mode, release the button to turn off."
Lockout
Lockout disables the switch against accidental activation, and the manual for the Olight Baton 4 EDC flashlight ($54.99, regular price, September 2026) says to lock it, "when the flashlight is off, press and hold the button (for about 2 seconds) until the Moonlight mode turns on and off."
Mode Memory
Mode memory means the light restarts in the last level you used; per the Baton 4 manual, "Moonlight, Low, Medium, and High modes will be memorized when turned off," Turbo returns as High, and Strobe is not memorized.
Turbo
Turbo is the highest output mode, usually held briefly: the Baton 4 lists Turbo at 1,300 lumens for 1.5 minutes before its first step.
Step-down
Step-down is the planned drop in output after a high mode runs for a set time, written by Olight with tildes, such as the Seeker 4 Pro's 4,600~1,200~600 lumens over 2.5 + 122 + 35 minutes.
Moonlight Mode
Moonlight mode is the lowest output, meant for dark-adapted eyes and long runtimes; the Baton 4 lists Moon at 0.5 lumens for 30 days.
Strobe
Strobe is a fast, repeating flash at full or near-full output, listed by Olight at "13Hz at 1,300 lumens" on the Baton 4.
Standards and Certification Terms
Standards terms tell you who measured a number and under what rules. ANSI/PLATO FL 1 governs flashlight performance claims in the U.S., and its current edition is FL 1-2025. IEC 60529 governs IP codes, the FDA governs laser classes, and the DOE describes LED lifetime. Many manuals still print older editions, so read the edition as well as the number.
ANSI/PLATO FL 1
ANSI/PLATO FL 1 is the U.S. standard for measuring and reporting portable light performance, written by PLATO, an ANSI-accredited standards developer, and now in its FL 1-2025 edition; the Baton 4 manual states its data were "tested per ANSI/PLATO FL 1-2019 standard in Olight's labs for reference," and the Warrior 3S manual cites "ANSI/NEMA FL1-2009."
Runtime
FL 1 runtime is "The duration of time from the initial light output value (that’s 30 seconds after the light is turned on with fresh batteries) until the light output drops to 10% of the initial value," per the pre-2025 Streamlight summary; PLATO says FL 1-2025 keeps the existing procedures for standard modes, and the Perun 3 manual rates its 25-hour Med figure under FL 1-2019.
Short-duration Elevated Brightness
Short-duration elevated brightness is the FL 1-2025 name for brief Turbo or Boost modes, and PLATO's FL 1-2025 summary says output is "measured between one and 10 seconds" and runtime lasts until output "drops to 90% of the highest measurement recorded during the first 10 seconds."
MAX Designation
The MAX designation is an FL 1-2025 marking on the lumen icon "to clarify that the reported value represents the highest output for the claimed mode," per PLATO.
IP Code
An IP code is the IEC 60529 rating (edition 1989 with 1999 and 2013 amendments) for protection against solids (first digit) and liquids (second digit); an X marks an unrated digit, and the Baton 4's IPX8 means immersion under conditions the maker sets, not a dive rating; our guide to IPX7 vs IPX8 vs IP68 covers the details.
Dust Rating
A dust rating is the first IP digit, which the IEC scales from 0 (no protection) to 6 (no ingress of dust), and FL 1-2025 adds its own dust ingress testing with "new icons for dust protection and combined dust and water protection"; the Perun 3 is rated IP68 and the Oclip 2 Pro IP66.
Laser Class
A laser class is the hazard category of a laser, and the FDA's laser products page maps FDA Class IIIa to IEC Class 3R, which "can be momentarily hazardous when directly viewed"; the Olight Arkfeld Pro flat EDC flashlight ($89.99, regular price, September 2026) lists its green laser as "Class 3R: 5 mW," so keep it away from children.
UV Wavelength
UV wavelength is the emission wavelength of an ultraviolet emitter in nanometers, listed as 365 nm on the Arkfeld Pro, and the Arkfeld Pro warning manual says, "Ultraviolet light: Do not look directly at the light source with the naked eye."
L70 Lifetime
L70 names the 70% point in the LED lifetime convention the DOE describes as "the number of operating hours until it is emitting 70% of its initial light output," used for LED lamps and fixtures rather than printed on flashlight spec sheets.
For who writes each standard and which edition applies, see our guide to the ANSI FL1 standard.
Carry and Form Terms
Carry terms describe the shape of a light and how it rides on you, which decides whether it leaves the house at all. Olight groups its pocket lights under EDC flashlights, and its pages use the form words below consistently.
EDC
EDC (everyday carry) means gear you keep on you daily, and Olight lists "Everyday Carry" as a use for the Warrior 3S and i3T 2 EOS.
Keychain Light
A keychain light is a very small light that hangs on a key ring, such as the 22 g i1R 2 Pro, which Olight rates at 180 lumens and 48 m.
Headlamp
A headlamp is a light worn on the head for hands-free work, and the Perun 3 ships with a headband so it can be used "as a headlight or flashlight."
Clip Light
A clip light attaches to clothing or gear; the Oclip 2 Pro pairs "a 115° head tilt with 360° clip rotation," and its manual warns, "If you have an ICD or pacemaker, avoid close or prolonged contact with this product to prevent possible interference."
Holster
A holster is a belt-mounted carrier, and the Warrior X 4 is sold "With Holster" while the Seeker 4 Pro can charge over "USB-C Charging (with Holster)."
Magnetic Tail
A magnetic tail is a magnet in the tail cap that lets the light stick to steel; Olight lists one on the Perun 3 so you can "attach it to any iron surface."
What Are the Parts of a Flashlight Called?
The parts of a flashlight, from front to back, are the bezel, lens, optic (TIR lens or reflector), LED emitter, driver circuit, body tube, battery, switch and tail cap. A clip, lanyard or magnetic tail may be added for carry. The head holds the light engine, the body holds the power, and the switch connects the two.
Walk through a Baton 4 as an example. The bezel and TIR optic lens form the face. Behind them sit the LED and the driver, the circuit that sets each mode's output. The body tube holds the customized 16340 cell. The side switch replaces a tail switch, and the MCC cable recharges the cell in about 1 hour, per the manual.
Tip: Before first use, check for a plastic insulating film on the battery. The Baton 4 manual says, "Remove the insulating film before use," and a new light that will not turn on often still has it in place.
What Are Some Common Lighting Terms?
Common lighting terms are the words shared by flashlights, bulbs and room lighting: lumen, candela, lux, CCT, CRI, flicker and lifetime. Flashlights add beam words such as throw, flood and hotspot, and portable-power words such as runtime and step-down. The shared terms follow the SI and CIE definitions, so the same word means the same thing everywhere.
A bulb's lumens spread around a room, while a flashlight's lumens are packed into a beam, so candela matters more. Flicker, which the CIE S 017:2020 vocabulary defines as the "perception of visual unsteadiness induced by a light stimulus" in its flicker entry, can be induced by "the light source itself, the power source or other influencing factors."
What Are Some Words Related to Flashlight?
Words related to flashlight include torch (the British English term), headlamp, penlight, lantern, spotlight, keychain light, clip light, weapon light and work light. Each names a form factor built for a job: lanterns light a room, spotlights reach far, penlights check close detail, and weapon lights mount on a rail. Olight's catalog groups them as EDC, tactical and mounted lights.
When you compare reviews from the U.K. and U.S., search both torch and flashlight.
Five Terms to Read First, by Scenario
The five terms to read first depend on the job: an EDC buyer should start with weight and sustained lumens, a searcher with candela and beam distance, and a camper with runtime and red light. Reading the right five in order cuts a long spec sheet to a few seconds. The framework below sets that order for six common jobs, using Olight figures as the test.
This table gives each scenario, the five flashlight terms to read in order, and the Olight figure that settles the choice.
| Scenario | Read these five terms, in order | The figure that settles it |
|---|---|---|
| Pocket EDC | Weight, step-down, lockout, charging type, IP code | Baton 4: 52.5 g, 300 lm after step-down, 2-second lockout |
| Power outage at home | Runtime, Med lumens, battery Wh, moonlight mode, charging type | Perun 3: Med 120 lm for 25 hours |
| Searching a field or yard | Peak beam intensity, beam distance, step-down, switch type, battery | Warrior X 4: 99,310 cd, 630 m, tail switch |
| Camping and hands-free | Form (headlamp), red light, Low runtime, weight, IP code | Perun 3: red 15 lm for 70 hours, IP68 |
| Repairs and color checks | CRI, CCT, flood mode, working temperature, magnetic tail | Perun 3 Mini HCRI: CRI 90, 4,000K to 5,000K |
| Rain, boats and mud | IP code, impact resistance, switch type, charging type, clip | Oclip 2 Pro: IP66, 2.0 m, but not for immersion |
The last row carries a warning. IP66 is a water-jet rating, not an immersion rating, and the Oclip 2 manual says, "Do not immerse the product in water or other liquids, as it will damage the product." For a light you might drop into water, read for IPX8 or IP68 instead.
Flashlight Glossary Mix-ups: Term Pairs People Confuse
The most common flashlight term mix-ups pair two words that sound alike but answer different questions: lumens and candela, mAh and Wh, IPX8 and IP66, CCT and CRI. Each pair has a one-line test that tells them apart on the spec sheet. The table below lists eight pairs and the line to check.
This table shows each confused pair, the real difference and where to check it on an Olight page.
| Pair people mix up | The difference | Where to check |
|---|---|---|
| Lumens vs candela | Total light vs intensity in one direction | Max Performance vs Max Light Intensity |
| Beam distance vs useful range | Distance to 0.25 lux vs distance you can identify things | Beam Distance line; expect far less for detail |
| Turbo vs sustained output | Brief peak vs the level after step-down | Tilde figures, such as 1,300~600~300 lumens |
| mAh vs Wh | Charge at one voltage vs energy across voltages | Compatible Batteries line; multiply V by Ah |
| IPX8 vs IP66 | Immersion rating vs powerful water jets plus dust | Waterproof or IP Rating line, then the manual |
| CCT vs CRI | Color of the light vs accuracy of object colors | Light Source line, such as CRI:90 |
| Lockout vs auto shut-off | Switch disabled vs timer that turns the light off | Manual operating steps |
| Tail switch vs side switch | Rear button vs body button, each with its own grip | Mode Operation line |
Three Worked Numbers That Tie the Terms Together
Three calculations show how the flashlight terms connect: charging time from mAh and charger current, output range from Turbo to Moon, and what the battery indicator's last step leaves in the cell. Each is arithmetic on Olight's published figures that you can repeat on any spec sheet, not a measurement.
- Charging time from mAh and current. The Baton 4 manual lists the MCC output as "CC & CV, 4.2V, 1A" and the cell as 650 mAh. At a constant 1 A, 0.65 Ah ÷ 1 A = 0.65 hours, or 39 minutes. The manual's "About 1 hour" leaves roughly 20 minutes for the constant-voltage (CV) finish, when current tapers as the cell fills.
- Output range, Turbo to Moon. The Baton 4 spans 1,300 / 0.5 = 2,600 to 1. The Warrior 3S spans 2,300 / 1 = 2,300 to 1. The Seeker 4 Pro spans 4,600 / 5 = 920 to 1, so its lowest mode is ten times brighter than the Baton 4's.
- What the red indicator leaves. The Baton 4 indicator turns red below 5%, and 5% of 650 mAh is 32.5 mAh. Moon runs 30 days, or 720 hours, on a full cell, so 5% is about 0.05 × 720 = 36 hours of Moon if the drain were even. Treat red as a signal to charge tonight.
The output range shows which light suits dark-adapted eyes: if you walk a dark house at 3 a.m., pick the light with the lower floor.
Safety note: Strobe and Turbo are bright enough to cause harm at close range. The Arkfeld Pro warning manual says, "Do not look directly at the light source or shine it into your eyes, as this may cause temporary blindness or permanent damage to your eyes."
Your Flashlight Terms Checklist
Use this checklist the next time a product page stops you. Each step points to one glossary entry and one spec sheet line. Start at the top and stop when the light fails a step that matters for your job.
- Read lumens with the tildes, and note the output after the first step-down.
- Read candela and beam distance together, and treat beam distance as a 0.25 lux edge.
- Read runtime for the mode you will use most, not for Turbo.
- Check the IP code, and confirm in the manual whether immersion is allowed.
- Note the cell size code and charging type, and whether spares are standard or customized.
- Check CCT and CRI if you work with color-coded wiring, paint or parts.
- Learn the lockout and mode memory steps on day one.
- Look for the FL 1 edition in the manual, and read older editions with that in mind.
FAQ
Changelog
- September 25, 2026: First published.
