diurnal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Relating to or occurring in a 24-hour period; daily.
• adjective Occurring or active during the daytime rather than at night.
• adjective Botany Opening during daylight hours and closing at night.
• noun A book containing all the offices for the daily canonical hours of prayer except matins.
• noun A diary or journal.
• noun A daily newspaper.

from The Century Dictionary.

• Of or belonging to day; pertaining to the daytime; belonging to the period of daylight, as distinguished from the night: opposed to nocturnal: as, diurnal heat; diurnal hours; diurnal habits, as of an animal.
• Daily; happening every day: as, a diurnal task.
• Performed in or occupying one day; lasting but for one day; ephemeral.
• Constituting the measure of a day, either on the earth or one of the other planets: as, the diurnal revolution of the earth, or of Mars or Jupiter.
• Characterized by some change or peculiarity which appears and disappears with the daytime,
• noun A day-book; a diary; a journal.
• noun A daily newspaper.
• noun A Roman Catholic service-book containing the offices for the daily hours of prayer.
• noun In ornithology, a diurnal bird of prey.
• noun In entomology, one of the Diurna.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Relating to the daytime; belonging to the period of daylight, distinguished from the night; -- opposed to nocturnal
• adjective Daily; recurring every day; performed in a day; going through its changes in a day; constituting the measure of a day
• adjective (Bot.) Opening during the day, and closing at night; -- said of flowers or leaves.
• adjective (Zoöl.) Active by day; -- applied especially to the eagles and hawks among raptorial birds, and to butterflies (Diurna) among insects.
• adjective (Anat.) the aberration of light arising from the effect of the earth's rotation upon the apparent direction of motion of light.
• adjective 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.
• adjective the apparent circle described by a celestial body in consequence of the earth's rotation.
• adjective the motion of the earth upon its axis which is described in twenty-four hours.
• adjective that apparent motion of the heavenly body which is due to the earth's diurnal motion.
• adjective See under Parallax.
• adjective the motion of the planet upon its own axis which constitutes one complete revolution.
• noun obsolete A daybook; a journal.
• noun (R. C. Ch.) A small volume containing the daily service for the “little hours,” viz., prime, tierce, sext, nones, vespers, and compline.
• noun (Zoöl.) A diurnal bird or insect.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Happening or occurring during daylight, or primarily active during that time.
• adjective botany Said of a flower open, or releasing its perfume during daylight hours, but not at night.
• adjective Having a daily cycle that is completed every 24 hours, usually referring to tasks, processes, tides, or sunrise to sunset.
• adjective uncommon Done once every day; daily, quotidian.
• adjective archaic Published daily.
• noun A flower that opens only in the day.
• noun Catholicism A book containing canonical offices performed during the day, hence not matins.
• noun archaic A diary or journal.
• noun archaic A daily news publication.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective of or belonging to or active during the day
• adjective having a daily cycle or occurring every day