light 1 |līt|noun1 the natural agent that stimulates sight and makes things visible: the light of the sun | [ in sing. ] : the street lamps shed a faint light into the room.• a source of illumination, esp. an electric lamp: a light came on in his room.• (lights) decorativeilluminations: Christmas lights.• a traffic light:turnright at thelight.• [ insing. ] an expressioninsomeone's eyes indicating a particular emotion or mood: a shrewd lightenteredhiseyes.• theamount or quality of light in a place: the plant requires good light | in some lights she could look beautiful.Visible light is electromagnetic radiation whose wavelength falls within the range to which thehumanretinaresponds, i.e., between about 390 nm (violet light) and 740 nm (red). White light consists of a roughly equalmixtureof allvisiblewavelengths, which can be separated to yield the colors of the spectrum, as was first demonstrated conclusively by Newton. In the 20th century it has become apparent that light consists of energy quanta called photons that behave partly like waves and partly like particles. The velocity of light in a vacuum is 299,792 kmper second.2 understanding of a problem or mystery; enlightenment: she saw light dawn on the woman's face.• spiritual illumination by divine truth.• (lights) a person's opinions, standards, and abilities: leaving the police to do the job according to their lights .3 an area of something that is brighter or paler than its surroundings: sunshine will brighten the natural lights in your hair.4 a device that makes something start burning, as a match, lighter, or flame: he asked me for a light.5 a window or opening in a wall to let light in.• any of the perpendicular divisions of a mullioned window.• any of the panes of glass forming the roof or side of a greenhouse or the top of a cold frame.6 a person notable or eminent in a particular sphere of activity or place: such lights of liberalism as the historian Goldwin Smith.verb ( past lit |lit|; past participle lit or lighted ) [ with obj. ]1 provide with light or lighting; illuminate: the room was lighted by a number of small lamps | lightning suddenlylit up the house.• switch on (an electric light): only one of the table lamps was lit.• [ no obj. ] (light up) become illuminated: the sign to fasten seat belts lit up.2 make (something) start burning; ignite: Allen gathered sticks and lit a fire | (as adj. lighted or lit) : a lighted cigarette.• [ no obj. ] begin to burn; be ignited: the gas wouldn't light properly.• (light something up) ignite a cigarette, cigar, or pipe and begin to smoke it: she lit up a cigarette and puffed on it serenely | [ no obj. ] : workers who light up in prohibited areas face dismissal.adjective1 having a considerable or sufficient amount of natural light; not dark: the bedrooms are light and airy | it was almost light outside.2 (of a color) pale: her eyes were light blue.PHRASESbring (or come ) to light make (or become) widely known or evident: an investigation to bring to light examples of extravagant expenditure.go out like a light informal fall asleep or lose consciousness suddenly.in a —— light in the way specified; so as to give a specified impression: the audit portrayed the company in a very favorable light.in ( the ) light of drawing knowledge or information from; taking (something) into consideration: the exorbitant prices are explainable in the light of the facts.light a fire under someone see fire.light at the end of the tunnel a long-awaited indication that a period of hardship or adversity is nearing an end.light the fuse see fuse2.the light of day daylight. • general public attention: bringing old family secrets into the light of day.the light of someone's life a much loved person.lights out bedtime in a school dormitory, military barracks, or other institution, when lights should be switched off.lit up informal, dated drunk.see the light understand or realize something after prolonged thought or doubt. • undergo religious conversion.see the light of day be born. • come into existence; be made public, visible, or available: this software first saw the light of day back in 1993.shed (or throw or cast ) light on help to explain (something) by providing further information about it.PHRASAL VERBSlight up (or light something up )(with reference to a person's face or eyes) suddenly become or cause to be animated with liveliness or joy: his eyes lit up and he smiled | a smile of delight lit up her face.DERIVATIVESlightish adjective,lightless adjective,lightness nounORIGIN Old English lēoht, līht (noun and adjective), līhtan (verb), of Germanic origin; related to Dutchlicht and German Licht, from an Indo-European root shared by Greek leukos ‘white’ and Latin lux‘light.’light 2 |līt|adjective1 of little weight; easy to lift: they are very light and portable | you're as light as a feather.• deficient in weight, esp. by a specified amount: the sack of potatoes is 5 pounds light.• not strongly or heavily built or constructed; small of its kind: light, impractical clothes | light armor.• carrying or suitable for small loads: light commercial vehicles.• carrying only light armaments: light infantry.• (of a vehicle, ship, or aircraft) traveling unladen or with less than a full load.• (of food or a meal) small in quantity and easy to digest: a light supper.• (of a foodstuff) low in fat, cholesterol, sugar, or other rich ingredients: stick to a light diet.• (of drink) not too sweet or rich in flavor or strongly alcoholic: a glass of light Hungarian wine.• (of food, esp. pastry or sponge cake) fluffy or well aerated during cooking.• (of soil) friable, porous, and workable.• (of an isotope) having not more than the usual mass; (of a compound) containing such an isotope.2 relatively low in density, amount, or intensity: passenger traffic was light | light summer breezes | trading was light for most of the day.• (of sleep or a sleeper) easily disturbed.• easily borne or done: he received a relatively light sentence | some light housework.3 gentle or delicate: she planted a light kiss on his cheek | my breathing was steady and light.• (of type) having thin strokes; not bold.4 (of entertainment) requiring little mental effort; not profound or serious: pop is thought of as light entertainment | some light reading.• not serious or solemn: his tone was light.• free from worry or unhappiness; cheerful: I left the island with a light heart.5 archaic (of a woman) unchaste; promiscuous.PHRASESbe light on be rather short of: light on hard news.be light on one's feet (of a person) be quick or nimble.a (or someone's ) light touch the ability to deal with something delicately, tactfully, or in an understated way: a novel that handles its tricky subject with a light touch.make light of treat as unimportant: I didn't mean to make light of your problems.make light work of accomplish (a task) quickly and easily.travel light travel with a minimum load or minimum luggage.DERIVATIVESlightish adjective,lightness nounORIGIN Old English lēocht, līht (noun), lēohte (adverb), of Germanic origin; related to Dutch licht andGerman leicht, from an Indo-European root shared by lung.light 3 |līt|verb ( past and past participle lit |lit| or lighted ) [ no obj. ]1 (light on/upon) come upon or discover by chance: he lit on a possible solution.2 archaic descend: from the horse he lit down.• (light on) fall and settle or land on (a surface): a feather just lighted on the ground.PHRASAL VERBSlight into informal criticize severely; attack: he lit into him for his indiscretion.light out informal depart hurriedly.ORIGIN Old English līhtan ( sense 2; also ‘lessen the weight of’), from light2; compare with alight1.