資料來源 : Webster's Revised Unabridged Dictionary (1913)
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}.