Main definitions of lumen in English

: lumen1lumen2

lumen1

(also LM)

noun

Physics
  • The SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela.

    • ‘In almost every case the electronic ballast ensures the highest mean lumens per watt, both by inherent efficiency and, in the case of metal halide lamps, by better lamp power management.’
    • ‘Today's lamps provide more lumens per watt than older ones, and the fixtures have been redesigned to more effectively use this light.’
    • ‘We ran the projector both in Eco mode, which is quieter, but only offers 800 lumens of output, and standard mode, which runs the fan at higher RPMs and pumps the light output to 1000 lumens.’
    • ‘For consumers who want higher lumens, manufacturers offer tactical lights utilizing Xenon or Halogen gas-filled bulbs with tungsten filaments.’
    • ‘The bulbs are very bright (measured in ‘lumens’ as in the more lumens the brighter the projector), allowing the images that they project to be seen even in well-lit rooms.’
    • ‘It comes with two lamps, one with 125 lumens output (one hour battery life) while the other offers 225 lumens (20 minutes of life).’
    • ‘Even on cloudy days, a tubular skylight can provide at least as much light as a 100-watt incandescent bulb - about 1,200 lumens.’
    • ‘Electric rather than magnetic ballast is to be preferred because it gives a more constant output, runs cooler and generates about 10% more lumens per watt.’
    • ‘In other words, for a light meter to read 1 foot-candle from a uniform point source of light that is 1 ft. away, a light source of about 12.57 lumens is required.’
    • ‘What we can buy is a compact fluorescent bulb that only uses 20 watts of electricity and produces 1,000 lumens, the same as a 100-watt light bulb.’
    • ‘There was at least 250 watts of lumens coming down from the ceiling which was considerably high - over ten feet.’
    • ‘On the positive side, standard metal halide offers high lumens per watt,, and fairly long life, both of which are important to building operators.’
    • ‘‘That said, you can still go down and buy a fluorescent lamp for a few dollars that puts out thousands of lumens,’ he says, compared to the 30 to 60 lm emitted by current white LEDs.’
    • ‘This 18-volt light offers 500 lumens of searing white light for 20 minutes, or you can employ the 250-lumen lamp assembly to extend run time to one hour.’
    • ‘A dinner candle, for example, generates about 12 lumens, while a 60-watt soft white incandescent bulb glows at around 840 lumens.’
    • ‘Some users might want ‘tactically blinding’ light - on the order of 90 lumens - but that could only come with double the battery load, more weight and bulk.’
    • ‘Operating on 6 volts, this light provides 60 lumens of brightness to identify and target, and can subdue suspects without having to fire a shot.’
    • ‘He or she attaches the illuminator to the light source, sets it at 1,000 lumens, and places the light source on standby to reduce the chance of burns.’
    • ‘It produces 25 lumens of white light without the distracting ‘black holes’ emitted by many flashlights.’
    • ‘It's that time of year when some of your neighbors have probably lit up the night with enough lumens to be seen from outer space.’

Origin

Late 19th century: from Latin, literally light.

Pronunciation:

lumen

/ˈlo͞omən/

Main definitions of lumen in English

: lumen1lumen2

lumen2

noun

Anatomy
  • The central cavity of a tubular or other hollow structure in an organism or cell.

    • ‘Fibrin and platelet thrombi were prominent in the lumina of the vessels and in the space beneath the endothelium.’
    • ‘These cells were found minimally invading the liver, by direct extension, but were readily found within the lumina of blood vessels and lymphatics.’
    • ‘Clear cell carcinoma may contain more ‘condensed’ nonclear cells with pink cytoplasm, mimicking ducts, albeit lacking lumina.’
    • ‘These loose columnals may have had soft matrix removed from the central lumina and, thus, would have been very bead-like in appearance.’
    • ‘Histologically, the disease is characterized by a bizarre population of neoplastic cells that are found systemically within the vascular lumina.’
    space, chamber, hollow, hole, pocket, pouch
    View synonyms

Origin

Late 19th century: from Latin, literally opening.

Pronunciation:

lumen

/ˈlo͞omən/