Emily Dickinson Lexicon

TWI'LIGHT, n. [Sax. tweon-leoht, doubtful light, from tweon, tweogan, to doubt, from twegen, two.]

1. The faint light which is reflected upon the earth after sunset and before sunrise; crepuscular light. In latitudes remote from the equator, the twilight is of much longer duration than at and near the equator.
2. Dubious or uncertain view; as, the twilight of probability. Locke.