1. (a.) Daily; Common; relating to the daytime -- opposed to nocturnal; as, diurnal heat; diurnal hours\.

2. (a.) 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.

3. (a.) Opening during the day, and closing at night; -- said of flowers or leaves.

4. (a.) Active by day; -- applied especially to the eagles and hawks among raptorial birds, and to butterflies (Diurna) among insects.

5. (n.) A daybook; a journal.

6. (n.) A small volume containing the daily service for the little hours, viz., prime, tierce, sext, nones, vespers, and compline.

7. (n.) A diurnal bird or insect.

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