- The light perceived before the rising, and after the setting, of the sun, or when the sun is less than 18° below the horizon, occasioned by the illumination of the earth's atmosphere by the direct rays of the sun and their reflection on the earth.
- faint light; a dubious or uncertain medium through which anything is viewed."As when the sun . . . from behind the moon, In dim eclipse, disastrous twilight sheds." [Milton.]"The twilight of probability." [Locke.]
Etymology: OE. twilight, AS. twi-see Twice) + leóht light; hence the sense of doubtful or half light; cf. LG. twelecht, G. zwielicht. See Light