early 15c., "servants of a household," from Latin familia "family servants, domestics collectively, the servants in a household," thus also "members of a household, the estate, property; the household, including relatives and servants," abstract noun formed from famulus "servant, slave," which is of unknown origin.
The Latin word rarely appears in the sense "parents with their children," for which domus (see domestic (adj.)) was used. Derivatives of famulus include famula "serving woman, maid," famulanter "in the manner of a servant," famulitas "servitude," familiaris "of one's household, private," familiaricus "of household slaves," familiaritas "close friendship."
In English, sense of "collective body of persons who form one household under one head and one domestic government, including parents, children, and servants, and as sometimes used even lodgers or boarders" [Century Dictionary] is from 1540s. From 1660s as "parents with their children, whether they dwell together or not," also in a more general sense, "persons closely related by blood, including aunts, uncles, cousins;" earlier "those who descend from a common progenitor, a house, a lineage" (1580s). Hence, "any group of things classed as kindred based on common distinguishing characteristics" (1620s); as a scientific classification, between genus and order, from 1753.
Latin familia often was glossed in Old English by hired, hyred "household, family, retinue" (for which see hide (n.2), and also by hiwscipe, hiwræden, hiwan "members of a family, household, or religious house," which is cognate with Old Norse hjon "one of the household; married couple, man and wife; domestic servant," and with Old High German hiwo "husband," hiwa "wife," also with Lithuanian šeimyna "family," Gothic haims "village," Old English ham "village, home" (see home (n.)). A 15c. glossary has, for Latin familia, Middle English a menge, from Anglo-French maisnie "the household, the whole attendance upon the personal establishment of the feudal lord."
As an adjective from c. 1600; with the meaning "suitable for a family," by 1807. Family values is recorded by 1966. Phrase in a family way "pregnant" is from 1796. Family circle is 1809; family man "man devoted to wife and children, man inclined to lead a domestic life" is 1856 (earlier it meant "thief," 1788, from family in a slang sense of "the fraternity of thieves"). Family tree "graph of ancestral relations" attested from 1752.
He was dressed in his best Coat, which had served him in the same Capacity before my Birth, and possibly, might be but little short in Antiquity, to the Root of his third Family Tree; and indeed, he made a venerable Figure in it. ["A Genuine Account of the Life and Transactions of Howell ap David Price, Gentleman of Wales," London, 1752]
late 14c., cicle, "perpetual circulating period of time, on the completion of which certain phenomena return in the same order," especially and originally in reference to astronomical phenomena, from Old French cicle and directly from Late Latin cyclus, from Greek kyklos "circle, wheel, any circular body," also "circular motion, cycle of events," from PIE kw(e)-kwl-o-, a suffixed, reduplicated form of the root *kwel- (1) "to revolve, move round."
From 1660s as "any recurring round of operations or events" (as in life cycle). From 1821 as "single complete period in a cycle." Extended by 1842 to "any long period of years, an age." In literary use, "the aggregate of the legends or traditions around some real or mythical event or character" (1835).
By 1884 as "recurring series of oscillations or operations in an engine, etc." From 1870 as short for motorcycle; by 1881 as short for bicycle or tricycle.
1842, "revolve in cycles, occur or recur in cycles," from cycle (n.). Meaning "to ride a bicycle" is by 1881 (implied in cycling). Related: Cycled.
Old English life (dative lif) "animated corporeal existence; lifetime, period between birth and death; the history of an individual from birth to death, written account of a person's life; way of life (good or bad); condition of being a living thing, opposite of death; spiritual existence imparted by God, through Christ, to the believer," from Proto-Germanic *leiban (source also of Old Norse lif "life, body," Old Frisian, Old Saxon lif "life, person, body," Dutch lijf "body," Old High German lib "life," German Leib "body"), properly "continuance, perseverance," from PIE root *leip- "to stick, adhere."
The noun associated with live (v.) "to live," which is literally "to continue, remain." Extended 1703 to inanimate objects, "term of duration or existence." Sense of "vitality, energy in action, expression, etc." is from 1580s. Meaning "conspicuously active part of human existence, pleasures or pursuits of the world or society" is by 1770s. Meaning "cause or source of living" led to the sense "vivifying or animating principle," and thus "one who keeps things lively" in life of the party (1787). Meaning "imprisonment for life, a life sentence" is from 1903. Paired alliteratively with limb from 1640s. Not on your life "by no means" is attested from 1896.
In gaming, an additional turn at play for a character; this transferred use was prefigured by uses in card-playing (1806), billiards (1856), etc., in reference to a certain number of chances or required objects without which one's turn at the game fails. The life "the living form or model, semblance" is from 1590s. Life-and-death "of dire importance" is from 1822; life-or-death (adj.) is from 1897. Life-jacket is from 1840; life-preserver from 1630s of anything that is meant to save a life, 1803 of devices worn to prevent drowning. Life-saver is from 1883, figurative use from 1909, as a brand of hard sugar candy from 1912, so called for shape.
Life-form is from 1861; life-cycle is from 1855; life-expectancy from 1847; life-history in biology from 1870; life-science from 1935. Life-work "the labor to which one's life has been devoted" is from 1848. Expression this is the life is from 1919; verbal shrug that's life is from 1924 (earlier such is life, 1778).
1941, named for Sir Hans Adolf Krebs (1900-1981), German-born British biochemist.
"life at ease," by 1902 (as Reilly), popularized in U.S. during World War I; it seems to have been military slang initially, sometimes said to trace to various songs but none of that title has been found.