twilight

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The diffused light from the sky during the early evening or early morning when the sun is below the horizon and its light is refracted by the earth's atmosphere.
2. n. The time of the day when the sun is just below the horizon, especially the period between sunset and dark.
3. n. Dim or diffused illumination.
4. n. A period or condition of decline following growth, glory, or success: in the twilight of his life.
5. n. A state of ambiguity or obscurity.

Century Dictionary and Cyclopedia

1. n. The light from the sky when the sun is below the horizon at morning and evening. It has generally been agreed by observers in different countries that this light rises in the morn-ing and sets in the evening when the sun is 18° or 19° below the horizon. The former depression is given by Ptolemy, Gemma Frisius, Magini, Kepler, and Gassendi; the value 19° is given by Posidonius and Alhazen. Under some circumstances a second twilight appears, separated by an interval of darkness from the first. Twilight is certainly due to reflection from the upper atmosphere, but the phenomenon is somewhat complicated by the zodiacal light.
2. n. Hence, any faint light; partial darkness; shade.
3. n. Figuratively, an indistinct medium of perception; also, a state of faint or hazy mental illumination.
4. Bolonging, pertaining, or peculiar to twilight; seen by twilight; crepuscular, as a hat or moth.
5. Faintly illuminated; shady; dim; obscure: either literally or figuratively.
6. To illuminate faintly or dimly.

Wiktionary

1. n. The soft light in the sky seen before the rising and (especially) after the setting of the sun, occasioned by the illumination of the earth’s atmosphere by the direct rays of the sun and their reflection on the earth.
2. n. The time when this light is visible; the period between daylight and darkness.
3. n. Any faint light through which something is seen; an in-between or fading condition.
4. adj. Pertaining to or resembling twilight.

GNU Webster's 1913

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. adj. Seen or done by twilight.
4. adj. Imperfectly illuminated; shaded; obscure.

WordNet 3.0

1. adj. lighted by or as if by twilight
2. n. a condition of decline following successes
3. n. the time of day immediately following sunset
4. n. the diffused light from the sky when the sun is below the horizon but its rays are refracted by the atmosphere of the earth