Crossword Dictionary

What's The Definition Of Diurnal?

\Di*ur"nal\, a. [L. diurnalis, fr. dies day. See {Deity}, and cf. {Journal}.] 1. Relating to the daytime; belonging to the period of daylight, distinguished from the night; -- opposed to {nocturnal}; as, diurnal heat; diurnal hours. 2. Daily; recurring every day; performed in a day; going through its changes in a day; constituting the measure of a day; as, a diurnal fever; a diurnal task; diurnal aberration, or diurnal parallax; the diurnal revolution of the earth. Ere twice the horses of the sun shall bring Their fiery torcher his diurnal ring. --Shak. 3. (Bot.) Opening during the day, and closing at night; -- said of flowers or leaves. 4. (Zo["o]l.) Active by day; -- applied especially to the eagles and hawks among raptorial birds, and to butterflies (Diurna) among insects. {Diurnal aberration} (Anat.), the aberration of light arising from the effect of the earth's rotation upon the apparent direction of motion of light. {Diurnal arc}, the arc described by the sun during the daytime or while above the horizon; hence, the arc described by the moon or a star from rising to setting. {Diurnal circle}, the apparent circle described by a celestial body in consequence of the earth's rotation. {Diurnal motion of the earth}, the motion of the earth upon its axis which is described in twenty-four hours. {Diurnal motion of a heavenly body}, that apparent motion of the heavenly body which is due to the earth's diurnal motion. {Diurnal parallax}. See under {Parallax}. {Diurnal revolution of a planet}, the motion of the planet upon its own axis which constitutes one complete revolution. Syn: See {Daily}.
\Di*ur"nal\, n. [Cf. F. diurnal a prayerbook. See {Diurnal}, a.] 1. A daybook; a journal. [Obs.] --Tatler. 2. (R. C. Ch.) A small volume containing the daily service for the ``little hours,'' viz., prime, tierce, sext, nones, vespers, and compline. 3. (Zo["o]l.) A diurnal bird or insect.