Etymology
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look (n.)
late Old English, "act or action of looking," from look (v.). Meaning "a particular instance of looking, a glance," especially one which conveys a certain feeling is from early 14c. Meaning "appearance of a person, visual or facial expression" is from late 14c. Looks with the same sense as the singular is from 1560s. Expression if looks could kill ..., of one seething silently, is attested by 1827 (if looks could bite is attested from 1747). Fashion sense "totality of appearance" is from 1938.
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for (prep.)
Old English for "before, in the sight of, in the presence of; as far as; during, before; on account of, for the sake of; in place of, instead of," from Proto-Germanic *fur "before; in" (source also of Old Saxon furi "before," Old Frisian for, Middle Dutch vore, Dutch voor "for, before;" German für "for;" Danish for "for," før "before;" Gothic faur "for," faura "before"), from PIE root *per- (1) "forward," hence "in front of, before," etc.

From late Old English as "in favor of." For and fore differentiated gradually in Middle English. For alone as a conjunction, "because, since, for the reason that; in order that" is from late Old English, probably a shortening of common Old English phrases such as for þon þy "therefore," literally "for the (reason) that."
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look (v.)

Old English locian "use the eyes for seeing, gaze, look, behold, spy," from West Germanic *lokjan (source also of Old Saxon lokon "see, look, spy," Middle Dutch loeken "to look," Old High German luogen, German dialectal lugen "to look out"), a word of unknown origin. Breton lagud "eye" has been suggested as a possible cognate.

In Old English, usually with on; the use of at began 14c. As a word to call attention, c. 1200 (look out! "take notice" is from mid-15c.). Meaning "seek, search out" is c. 1300; meaning "to have a certain appearance, express or manifest by looks" is from c. 1400. Of objects, "to face in a certain direction," late 14c. To look like "have the appearance of" is from mid-15c. Look after "take care of" is from late 14c., earlier "to seek" (c. 1300), "to look toward" (c. 1200). Look into "investigate" is from 1580s. To look forward "anticipate" is c. 1600; especially "anticipate with pleasure" from mid-19c. To look over "scrutinize" is from mid-15c.

Look up is from c. 1200 in literal sense "raise the eyes;" as "research in books or papers" from 1690s. To look up to "regard with respect and veneration" is from 1719. To look down upon in the figurative sense "regard as beneath one" is from 1711; to look down one's nose is from 1921. To not look back "make no pauses" is colloquial, first attested 1893. In look sharp (1711), sharp originally was an adverb, "sharply." To look around "search about, look round" is from 1883.

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look-see (n.)
"inspection," 1865, "Pidgin-like formation" [OED], first used in representations of English as spoken by Chinese, from look (v.) + see (v.).
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look-alike (n.)
"someone who closely resembles another," 1937, American English, from look (v.) + alike.
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good-for-nothing (adj.)
"worthless," 1711, from adjectival phrase (see good (adj.)).
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free-for-all (n.)
"mass brawl" (one in which all may participate), 1918, from earlier adjective use (1868), especially in reference to open horse races, American English. Earlier as a noun in reference to free-for-all horse and motorcar races.
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expect (v.)

1550s, "wait, defer action," from Latin expectare/exspectare "await, look out for; desire, hope, long for, anticipate; look for with anticipation," from ex- "thoroughly" (see ex-) + spectare "to look," frequentative of specere "to look at" (from PIE root *spek- "to observe").

The figurative sense of "anticipate, look forward to" developed in Latin and is attested in English from c. 1600. Also from c. 1600 as "regard as about to happen." Meaning "count upon (to do something), trust or rely on" is from 1630s. Used since 1817 as a euphemism for "be pregnant." In the sense "suppose, reckon, suspect," it is attested from 1640s but was regarded as a New England provincialism. Related: Expected; expecting.

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show (v.)

Old English sceawian "to look at, see, gaze, behold, observe; inspect, examine; look for, choose," from Proto-Germanic *skauwojan (source also of Old Saxon skauwon "to look at," Old Frisian skawia, Dutch schouwen, Old High German scouwon "to look at"), from Proto-Germanic root *skau- "behold, look at," from PIE *skou-, variant of root *keu- "to see, observe, perceive."

Causal meaning "let be seen; put in sight, make known" evolved c. 1200 for unknown reasons and is unique to English (German schauen still means "look at"). Spelling shew, popular 18c. and surviving into early 19c., represents obsolete pronunciation (rhymes with view). Horse racing sense is from 1903, perhaps from an earlier sense in card-playing.

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lookit (interj.)
noted by 1917 in schoolyard talk for look at.
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