mid-15c., "make clean," from clean (adj.). Related: Cleaned; cleaning. From clean out "clean by emptying" comes sense of "to leave bare" (1844); cleaned-out "left penniless by losses" is from 1812.
c. 1300 as an adverbial phrase, "completely, thoroughly, to the utmost degree," from out (adv.). Adjective usage is attested by 1813.
Old English clæne "free from dirt or filth, unmixed with foreign or extraneous matter; morally pure, chaste, innocent; open, in the open," of beasts, "not forbidden by ceremonial law to eat," from West Germanic *klainja- "clear, pure" (source also of Old Saxon kleni "dainty, delicate," Old Frisian klene "small," Old High German kleini "delicate, fine, small," German klein "small;" English preserves the original Germanic sense), perhaps from PIE root *gel- "bright, gleaming" (source also of Greek glene "eyeball," Old Irish gel "bright"). But Boutkan doubts the IE etymology and that the "clean" word and the "small" word are the same.
"Largely replaced by clear, pure in the higher senses" [Weekley], but as a verb (mid-15c.) it has largely usurped what once belonged to cleanse. Meaning "whole, entire" is from c. 1300 (clean sweep in the figurative sense is from 1821). Sense of "not lewd" (as in good, clean fun) is from 1867; that of "not carrying anything forbidden" is from 1938; that of "free of drug addiction" is from 1950s. To come clean "confess" is from 1919, American English.
Old English clæne "dirtlessly," also "clearly, fully, entirely;" see clean (adj.). Compare similar use of German rein "clean."
in Old English a common prefix with nouns, adjectives, adverbs, and verbs, "out, outward, outer; forth, away," from out (adv.). The use was even more common in Middle English, and also with the senses "outer, outside, on the outside, from without, external, externally; apart; greatly, extremely; completely, thoroughly, to completion." Other senses of out that extended into the use as a prefix include "beyond the surface or limits; to the utmost degree; to an explicit resolution."
In composition out has either its ordinary adverbial sense, as in outcast, outcome, outlook, etc., or a prepositional force, as in outdoors, or forms transitive verbs denoting a going beyond or surpassing of the object of the verb, in doing the act expressed by the word to which it is prefixed, as in outrun, outshine, outvenom, etc. In the last use especially out may be used with almost any noun or verb. [Century Dictionary]
Old English utian "expel, put out," from the source of out (adv.). It has been used in many specific senses over the years; the meaning "disclose to public view, reveal, make known" is by mid-14c.
Eufrosyne preyde Þat god schulde not outen hire to nowiht. ["Legendary of St. Euphrosyne," c. 1350]
Meaning "to expose as a closet homosexual" is first by 1990 (as an adjective meaning "openly avowing one's homosexuality" it dates from 1970s; see closet). To come out "declare oneself publicly as homosexual" is from 1968 and probably short for come out of the closet. Related: Outed; outing. Compare outen.
late Old English, "outer," from out (adv.). From mid-13c. as "that is or lies on the outside, exterior." Of a light or candle, "extinguished, no longer burning," c. 1300. Sense of "no longer secret" is by 1713. Sense in baseball (1860) was earlier in cricket (1746). Meaning "unconscious" is attested from 1898, originally in boxing from the notion of "defeated ('out') by failing to rise within a 10-count." To be out on one's feet is from 1952. From 1966 as "unfashionable, not stylish, popular, or modern."
expressing motion or direction from within or from a central point, also removal from proper place or position, Old English ut "out, without, outside," from Proto-Germanic *ūt- (Old Norse, Old Frisian, Old Saxon, Gothic ut, Middle Dutch uut, Dutch uit, Old High German uz, German aus), from PIE root *uidh- "up, out, up away, on high" (source also of Sanskrit ut "up, out," uttarah "higher, upper, later, northern;" Avestan uz- "up, out," Old Irish ud- "out," Latin usque "all the way to, continuously, without interruption," Greek hysteros "the latter," Russian vy- "out").
Sense of "to a full end, completely, to a conclusion or finish" is from c. 1300. Meaning "so as to be no longer burning or alight; into darkness" is from c. 1400. Of position or situation, "beyond the bounds of, not within," early 15c. Meaning "into public notice" is from 1540s; that of "away from one's place of residence," c. 1600. The political sense of "not in office, removed or ejected from a position" is from c. 1600. Meaning "come into sight, become visible" (of stars, etc.) is by 1610s. In radio communication, a word indicating that the speaker has finished speaking, by 1950.
As a preposition, "out of; from, away from; outside of, beyond; except; without, lacking;" mid-13c., from the adverb.
Meaning "from harmonious relations, into quarreling" (as in to fall out) is from 1520s. Meaning "from one's normal state of mind" (as in put out) is from 1580s; out to lunch "insane" is student slang from 1955. Adjectival phrase out-of-the-way "remote, secluded" is attested from late 15c. Out-of-towner "one not from a certain place" is from 1911. Out of this world "excellent" is from 1938; out of sight "excellent, superior" is from 1891. To (verb) it out "bring to a finish" is from 1580s. Expression from here on out "henceforward" is by 1942. Out upon, expressing abhorrence or reproach, is from early 15c.
also cleanup, 1856, "act of cleaning up, a general cleaning," from clean + up. Meaning "a profit" is recorded from 1878. Verbal phrase clean up "make a large profit" is from 1929. The adjective, in the baseball sense, is recorded by 1910 in reference to the hitter who bats fourth in the lineup: His job is to drive in runs by scoring the players who hit before him and thus "clean up" the bases.