U

cheeks

noun

either side of the face below the eye and above the jaw.
the side wall of the mouth between the upper and lower jaws.
something resembling the side of the human face in form or position, as either of two parts forming corresponding sides of various objects: the cheeks of a vise.
impudence or effrontery: He’s got a lot of cheek to say that to me!
Slang. either of the buttocks.
Architecture.
1. one side of an opening, as a reveal.
2. either of two similar faces of a projection, as a buttress or dormer.
Carpentry.
1. a piece of wood removed from the end of a timber in making a tenon.
2. a piece of wood on either side of a mortise.
one side of a hammer head.
Horology. one of two pieces placed on both sides of the suspension spring of a pendulum to control the amplitude of oscillation or to give the arc of the pendulum a cycloidal form.
one of the two main vertical supports forming the frame of a hand printing press.
Machinery. either of the sides of a pulley or block.
Nautical. either of a pair of fore-and-aft members at the lower end of the head of a lower mast, used to support trestletrees which in turn support a top and often the heel of a topmast; one of the hounds of a lower mast.
Metallurgy. any part of a flask between the cope and the drag.

Idioms

cheek by jowl, in close intimacy; side by side: a row of houses cheek by jowl.
(with) tongue in cheek. tongue(def 37).

noun

1. either side of the face, esp that part below the eye
2. either side of the oral cavity; side of the mouthRelated adjectives: buccal, genal, malar
informal impudence; effrontery
(often plural) informal either side of the buttocks
(often plural) a side of a door jamb
nautical one of the two fore-and-aft supports for the trestletrees on a mast of a sailing vessel, forming part of the hounds
one of the jaws of a vice
cheek by jowl close together; intimately linked
turn the other cheek to be submissive and refuse to retaliate even when provoked or treated badly
with one’s tongue in one’s cheek See tongue (def. 19)

verb

(tr) informal to speak or behave disrespectfully to; act impudently towards

“the buttocks,” c.1600; see cheek.

Old English ceace, cece “jaw, jawbone,” in late Old English also “the fleshy wall of the mouth.” Perhaps from the root of Old English ceowan “chew” (see chew (v.)), or from Proto-Germanic *kaukon (cf. Middle Low German kake “jaw, jawbone,” Middle Dutch kake “jaw,” Dutch kaak), not found outside West Germanic.

Words for “cheek,” “jaw,” and “chin” tend to run together in IE languages (e.g. 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).

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 “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 Matt. v:39 and Luke vi:29.

The fleshy part of either side of the face below the eye and between the nose and ear.
Either of the buttocks.

In addition to the idiom beginning with cheek

cheek by jowl

also see:

tongue in cheek
turn the other cheek