From Middle English twilight, twyelyghte, equivalent to twi- (“double, half-”) +‎ light, literally ‘second light, half-light’. Cognate to Scots twa licht, twylicht, twielicht (“twilight”), Low German twilecht, twelecht (“twilight”), Dutch tweelicht (“twilight, dusk”), German Zwielicht (“twilight, dusk”). Compare Old English twēone lēoht (“twilight”).

• IPA^(key): /ˈtwaɪˌlaɪt/

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twilight (countable and uncountable, plural twilights)

1. The soft light in the sky seen before the rising and (especially) after the setting of the sun, occasioned by the illumination of the earth’s atmosphere by the direct rays of the sun and their reflection on the earth.

   Near-synonym: half-light

   I could just make out her face in the twilight.

2. The time when this light is visible; the period between daylight and darkness.

   Hyponyms: dawn, dusk

   It was twilight by the time I got back home.

   • 1892, Walter Besant, chapter II, in The Ivory Gate […], New York, N.Y.: Harper & Brothers, […], →OCLC:

     At twilight in the summer there is never anybody to fear—man, woman, or cat—in the chambers and at that hour the mice come out. They do not eat parchment or foolscap or red tape, but they eat the luncheon crumbs.

3. Any faint light through which something is seen.
   • 1927, Willa Cather, Death Comes for the Archbishop, Book VII, section 4, page 233:

     Two women, Eusabio’s wife and sister, looked on from the deep twilight of the hut.

4. (astronomy) The time when the sun is less than 18° below the horizon.
5. (figurative, by extension) An in-between or fading condition through which something is perceived.

   The twilight of one's life

   • 1689 (indicated as 1690), [John Locke], An Essay Concerning Humane Understanding. […], London: […] Eliz[abeth] Holt, for Thomas Basset, […], →OCLC:
     , Book IV, Chapter XIV

     The twilight […] of probability.

   • 1846 October 1 – 1848 April 1, Charles Dickens, Dombey and Son, London: Bradbury and Evans, […], published 1848, →OCLC:

     “They have not enough heart,” said Edith, with a smile. The very twilight of a smile: so singularly were its light and darkness blended.

• (period between daylight and darkness): blue hour, gloaming; see also Thesaurus:twilight

• light

• (period between daylight and darkness): cockcrow, first light / evenfall, eventide; see also Thesaurus:dawn and Thesaurus:dusk

• astronomical twilight
• civil twilight
• nautical twilight

• dawn (end of ~ in the morning)
• dusk (end of ~ in the evening)
• evening
• golden hour
• nightfall
• sundown

• twilight anesthesia
• twilight industry
• twilight language
• twilightish
• Twilight of the Gods
• twilight shift
• twilights
• twilighty
• twilight sleep
• twilight years
• twilight zone
• twilit

twilight (not comparable)

1. Pertaining to or resembling twilight; faintly illuminated; obscure.
   • 1717, Alexander Pope, “Eloisa to Abelard”, in The Works of Mr. Alexander Pope, volume (please specify |volume=I or II), London: […] W[illiam] Bowyer, for Bernard Lintot, […], published 1717, →OCLC:

• crepuscular

twilight (third-person singular simple present twilights, present participle twilighting, simple past and past participle twilit or twilighted)

1. (transitive, poetic) To illuminate faintly.