Twi'/light (-lit)1, n.
[From A-S. twi, two, and Eng. light; L. Ger. twelecht, H. Ger. zwielicht, A-S. tweonleóht, i. e., doubtful light, from tweóna, doubt, from tweógan, tweógan, to doubt, from twi, twig, two, and leóht, light.]
Sense 1. The faint light perceived before the rising and after the setting of the sun, or when he is less than 18° below the horizon, occasioned by the illumination of the earth's atmosphere by the direct rays of the sun; crepuscular light.
Sense 2. Hence, a faint light in general; a dubious or uncertain view. “The twilight of probability.” Locke.
As when the sun . . . from behind the moon, In dim eclipse, disastrous twilight sheds. Milton.