Noah Webster's New International Dictionary of the English Language
1. (n.) 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.
2. (n.) faint light; a dubious or uncertain medium through which anything is viewed.
3. (a.) Seen or done by twilight.
4. (a.) Imperfectly illuminated; shaded; obscure.