Etymology
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cheek (n.)

"either of the two fleshy sides of the face below the eyes," Old English ceace, cece "jaw, jawbone," in late Old English also "the fleshy wall of the mouth," of uncertain origin, from Proto-Germanic *kaukon (source also of Middle Low German kake "jaw, jawbone," Middle Dutch kake "jaw," Dutch kaak), not found outside West Germanic, probably a substratum word.

Words for "cheek," "jaw," and "chin" tend to run together in IE languages (compare PIE *genw-, source of Greek genus "jaw, cheek," geneion "chin," and English chin); Aristotle considered the chin as the front of the "jaws" and the cheeks as the back of them. The other Old English word for "cheek" was ceafl (see jowl (n.1)).

A thousand men he [Samson] slow eek with his hond, And had no wepen but an asses cheek. [Chaucer, "Monk's Tale"]

In reference to the buttocks from c. 1600. Sense of "brazen insolence" is from 1840, perhaps from a notion akin to that which led to jaw "insolent speech," mouth off, etc. To turn the other cheek is an allusion to Matthew v.39 and Luke vi.29. Cheek-by-jowl "with cheeks close together," hence "in intimate contact" is from 1570s; earlier in same sense was cheek-by-cheek (early 14c.). In ballroom dancing, cheek-to-cheek is from 1919 (earlier it was a measurement of apples). 

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cheeks (n.)
"the buttocks," c. 1600; see cheek.
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cheeky (adj.)

"impudent, presumptuous," 1859 (1850 as the nickname of a misbehaving boy in a story), from cheek in its sense of "insolence" + -y (2). Related: Cheekily; cheekiness (1841). 

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chock-full (adj.)

c. 1400, chokkeful "crammed full," first element possibly from choke "cheek" (see cheek (n.)). Or it may be from Old French choquier "collide, crash, hit" (13c., Modern French choquer), which is probably from Germanic (compare Middle Dutch schokken; see shock (n.1)).

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leer (v.)
1520s, "to look obliquely" (since 18c. usually implying a lustful, wolfish, malicious intent), probably from Middle English noun ler "cheek," from Old English hleor "the cheek, the face," from Proto-Germanic *hleuza- "near the ear," from *hleuso- "ear," from PIE root *kleu- "to hear." If so, the notion is probably of "looking askance" (compare the figurative development of cheek). Related: Leered; leering.
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tongue-in-cheek (adv.)

1856, from phrase to speak with one's tongue in one's cheek "to speak insincerely" (1748), suggestive of sly irony or humorous insincerity, perhaps a stage trick to convey irony to the audience.

Hem! Pray, Sir, said he to the Bard, after thrusting his Tongue into a Corner of his Cheek, and rolling his Eyes at Miss Willis, (Tricks which he had caught by endeavouring to take off a celebrated Comedian) were these fine Tragedies of yours ever acted? [anonymous, "Emily, or the History of a Natural Daughter," 1761]
This arietta, however, she no sooner began to perform, than he and the justice fell asleep ; but the moment she ceased playing, the knight waked snorting, and exclaimed,—'O cara! what d'ye think, gentlemen? Will you talk any more of your Pargolesi and your Corelli ?'—At the same time, he thrust his tongue in one cheek, and leered with one eye at the doctor and me, who sat on his left hand—He concluded the pantomime with a loud laugh, which he could command at all times extempore. [Smollett, "The Expedition of Humphrey Clinker," 1771]
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choke (v.)

c. 1300, transitive, "to stop the breath by preventing air from entering the windpipe;" late 14c., "to make to suffocate, deprive of the power of drawing breath," of persons as well as swallowed objects; a shortening of acheken (c. 1200), from Old English aceocian "to choke, suffocate," probably from root of ceoke "jaw, cheek" (see cheek (n.)), with intensive a-.

Intransitive sense from c. 1400. Meaning "gasp for breath" is from early 15c. Figurative use from c. 1400, in early use often with reference to weeds stifling the growth of useful plants (a Biblical image). Meaning "to fail in the clutch" is attested by 1976, American English. Related: Choked; choking.

The North American choke-cherry (1785) supposedly was so called for its astringent qualities: compare choke-apple "crab-apple" (1610s); and choke-pear (1530s) "kind of pear with an astringent taste" (also with a figurative sense, defined by Johnson as "Any aspersion or sarcasm, by which another person is put to silence)." Choked up "overcome with emotion and unable to speak" is attested by 1896. The baseball batting sense is by 1907.

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chin (n.)

"lower extremity of the face below the mouth," Old English cin, cinn "chin," a general Germanic word (compare Old Saxon and Old High German kinni; Old Norse kinn; German Kinn "chin;" Gothic kinnus "cheek"), from PIE root *genu- (2), probably originally "jaw, jawbone," but also forming words for "chin, cheek."

The West Germanic words generally mean "chin," but there are traces of earlier use as "jaw," such as Old English cinbane "jawbone," and the words for "cheek," "chin," and "jaw" naturally overlap and interchange; compare cheek (n.), which originally meant "jaw," and Latin maxilla, which gave Italian mascella "jaw," but Spanish mejilla "cheek."

To take it on the chin "be hit hard" in a figurative sense (sometimes suggesting "ability to withstand punishment"), is from 1924, an image from pugilism. To keep (one's) chin up "remain optimistic amid adversity" is from 1913, though the image itself is older.

I discovered the other day another simple means of producing cheerfulness—raise the chin—with the chin up, the whole mental attitude is changed. If you feel a bit blue or discouraged, just raise your chin, and you will find that things look different; whereas the mere appearance of a man with his chin down suggests that he is disconsolate. [National Magazine, November 1906] 
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buccal (adj.)

"pertaining to the cheek," 1813, from Latin bucca "cheek," especially when puffed out (later "mouth"); see bouche.

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gnathic (adj.)

"pertaining to the jaw," 1882, with -ic + Greek gnathos "jaw, cheek," properly "the lower jaw," from PIE root *genu- (2) "jawbone, chin."

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