also pay-day, "day when payment is to be made or debts are to be discharged," 1520s, from pay (n.) + day.

late 14c., originally a medical term, from Medieval Latin ephemera (febris) "(fever) lasting a day," from fem. of ephemerus, from Greek ephemeros "daily, for the day," also "lasting or living only one day, short-lived," from epi "on" (see epi-) + hēmerai, dative of hēmera "day," from PIE *Hehmer "day." Sense extended 17c. to short-lived insects (Modern Latin ephemera musca) and flowers; general sense of "thing of transitory existence" is first attested 1751. Compare Greek ephemeroi "men," literally "creatures of a day."

Old English wicudæge, wucudæge "day of the week" (similar formation in Old High German wehhatag, Old Norse vikudagr). See week + day. In Middle English, any day other than Sunday.

late 14c., "daily, happening every day," from Late Latin diurnalis "daily," from Latin dies "day" + -urnus, an adjectival suffix denoting time (compare hibernus "wintery"). Dies "day" is from PIE root *dyeu- "to shine" (source also of Sanskrit diva "by day," Welsh diw, Breton deiz "day;" Armenian tiw; Lithuanian diena; Old Church Slavonic dini, Polish dzień, Russian den).

From early 15c. as "performed in or occupying one day;" 1620s as "of or belonging to the daytime (as distinguished from nocturnal). Related: Diurnally.

"last day of December," also a refreshment given that day, 1670s, of uncertain origin.

Old English geol, geola "Christmas Day, Christmastide," which is cognate with Old Norse jol (plural), the name of a heathen feast, later taken over by Christianity; the Germanic word is of unknown origin. The Old English (Anglian) cognate giuli was the Anglo-Saxons' name for a two-month midwinter season corresponding to Roman December and January, a time of important feasts but not itself a festival.

After conversion to Christianity the word narrowed to mean "the 12-day feast of the Nativity" (which began Dec. 25), but was replaced by Christmas by 11c., except in the northeast (areas of Danish settlement), where it remained the usual word.

Revived 19c. by writers to mean "the Christmas of 'Merrie England.' " First direct reference to the Yule log is 17c. According to some sources, Old Norse jol was borrowed into Old French as jolif, hence Modern French joli "pretty, nice," originally "festive" (see jolly).

"part of a newspaper's staff that works during the day," by 1942, American English, from day (n.) + side (n.).

c. 1200, werkedei (n.), "day designated for labor rather than religious observance or rest," from Old Norse virkr dagr "working day;" see work (n.) + day. It passed into an adjective 16c.

"indefinitely," Latin, literally "without (fixed) day," from sine "without" (see sans) + ablative singular of dies "day" (from PIE root *dyeu- "to shine"). Used of adjournments without any specified day or time for reassembling.

late 14c., "by day; on or in the day or time," with adverbial genitive -s from earlier aday (mid-13c.), prepositional phrase used as an adverb, from a- (1) "on, on each" + day (n.). The genitive ending now is regarded as an accusative plural.