Twilight Twi"light`, n. [OE. twilight, AS. twi- (see {Twice}) + le['o]ht light; hence the sense of doubtful or half light; cf. LG. twelecht, G. zwielicht. See {Light}.] [1913 Webster] 1. The light perceived before the rising, and after the setting, of the sun, or when the sun is less than 18[deg] 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. [1913 Webster]

2. faint light; a dubious or uncertain medium through which anything is viewed. [1913 Webster]

As when the sun . . . from behind the moon, In dim eclipse, disastrous twilight sheds. --Milton. [1913 Webster]

The twilight of probability. --Locke. [1913 Webster]

The Collaborative International Dictionary of English. 2000.