lm

/ɛl ɛm/
noun
  1. A unit of measurement for light, equal to the amount of light emitted by one candle; short for lumen.
    • This light bulb produces 800 lm of brightness.
    • The flashlight has a rating of 300 lm.
    • For a reading lamp, you need at least 450 lm.
  2. An abbreviation for 'lumen' used in technical contexts.
    • Check the lm output before buying a projector.
    • The lm value tells you how bright the light will be.
    • The package says '800 lm' on the label.