OED:
twilight, n.
1. The light diffused by the reflection of the sun's rays from the atmosphere before sunrise, and after sunset; the period during which this prevails between daylight and darkness.
1796 J. Morse American Universal Geography (new ed.) I. 52 The twilight is that faint light which opens the morning by little and little in the east, before the sun rises; and gradually shuts in the evening in the west, after the sun is set.
