The IES defines illumination engineering terms in ANSI/IES LS-1-22, is available here online. You can search terms by their first letter using the categories listed in the Categories window, by the first letter of the term in the alphabetical list below, or by typing the term in the search window. You can find the Introduction material for LS-1-22 on these pages:
Copyright, Disclaimer, and American National Standards Statement
Foreword, Nomenclature Committee members, Introduction, and Scope
- light output ratio
- light plot
- light source color
- light source description (for risk group classification)
- light trespass
- lighting-cooling index
- lighting effectiveness factor, LEF
- lighting zone (exterior lighting)
- lighting zone (interior lighting controls)
- lightness (of a perceived patch of surface color)
- linear light
- linear polarization
- Linnebach projector
- loader
- Local Chroma Shift (Rcs,hj)
- Local Color Fidelity (Rf,hj)
- Local Hue Shift (Rhs,hj)
- local lighting
- localized general lighting
- long-arc lamp
- longitudinal roadway line, LRL
- louver (or louver grid)
- louver shielding angle, θ
- louvered ceiling
- low-bay lighting
- low-key lighting
- low-pressure mercury germicidal lamp
- low pressure mercury lamp
- low pressure sodium (LPS) lamp
- lower (passing) beams
- lumen
- lumen (or flux) method
- lumen-second
- luminaire
- luminaire ambient temperature factor
- luminaire dirt depreciation, LDD
- luminaire efficiency
- luminaire spacing criterion, SC
- luminaire surface depreciation factor
- luminance
- luminance coefficient, LC
- luminance contrast
- luminance contrast sensitivity
- luminance difference
- luminance difference threshold
- luminance factor, β
- luminance ratio
- luminance threshold
- luminescence
- luminous ceiling
- luminous efficacy of a source
- luminous efficacy of radiant flux
- luminous energy
- luminous exitance
- luminous fluence
- luminous fluence rate
- luminous flux
- luminous flux density at a surface
- luminous flux maintenance
- luminous intensity
- luminous intensity distribution curve
- luminous range
- luminous reflectance
- luminous sterisent
- luminous transmittance
- lux
- lux meter
- maintenance factor (MF)
- Martingale
- master
- matte
- matte surface
- mean horizontal intensity (candlepower)*
- mean spherical luminous intensity
- mean zonal candlepower
- means of egress
- median life
- memory
- mercury-fluorescent lamp (phosphor mercury lamp)
- mercury lamp
- mesopic vision
- message
- metal halide lamp
- metamerism
- metamers
- meteorological optical range
- midget
- Mie scatter
- minimal perceptible erythema
- minimum erythemal dose
- MIRED
- modeling light
- modulation threshold
- monocular visual field
- motion detector
- mounting height, MH (interior)
- mounting height, MH (roadway)
- multiple-beam headlamp
- Munsell chroma
- Munsell color system