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
- Munsell hue
- Munsell value
- nanometer (nm)
- narrow-angle diffusion
- narrow-angle luminaire
- national standard of light
- navigation light system
- near field
- night
- nit (nt)
- nocturnal
- nominal range of a light signal
- non-dim circuit
- non-general lighting source lamp
- non-lens spotlight
- nonrecoverable light loss factor (initial or maintained)
- Obie light
- object color
- obstruction beacon
- obstruction lights (aeronautical lighting)
- occulting light
- occupancy sensor
- olivette
- on-off ratio (or mark-space ratio) for a repeated single flash
- one-K
- opaque medium
- opponent channels
- optical radiation
- organic light emitting diode (OLED)
- orientation
- Ostwald color system
- overcast sky
- overhang
- overhead (or butterfly)
- ozone-producing radiation
- paddle
- panel face exit sign
- pantograph
- PAR lamp
- par light
- parabolic spotlight
- parallel (television, film, theater)
- parking lamp
- partial diffusion
- partly cloudy sky
- passing beams
- patch
- patch panel
- pattern spotlight
- peak wavelength (λp)
- pendant luminaire
- perceived chroma of an area of surface color
- perceived color
- perceived light source color
- percent flicker
- perfect diffusion
- perimeter lights
- period life
- peripheral vision
- peripheral visual field
- personal tuning
- phantom
- phosphor mercury lamp
- phosphorescence
- phot-
- phot
- photobiological hazard
- photobiological (human) hazard function
- photobiology
- photocarcinogenesis
- photocataractogenesis
- photochemical radiation
- photochemotherapy
- photoconjunctivitis
- photocontrol
- photocuring
- photodynamic therapy
- photoeffect
- photoflash lamp
- photoflood lamp
- photokeratitis
- photokeratoconjunctivitis
- photometer
- photometric brightness
- photometry
- photomorphogenesis
- photomutagenesis
- photon
- photon flux maintenance
- photon flux (Φp)
- photoperiod
- photoperiodism
- photopic vision
- photoretinitis
- photosensitization
- photosynthesis
- photosynthetic irradiance
- photosynthetic photon flux density (PPFD)
- photosynthetically active radiation (PAR)
- phototaxis