chock-full (adj.)

"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 substrate 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. The 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). 

1560s, "violent encounter of armed forces or a pair of warriors," a military term, from French choc "violent attack," from Old French choquer "strike against," probably from Frankish, from a Proto-Germanic imitative base (compare Middle Dutch schokken "to push, jolt," Old High German scoc "jolt, swing").

The general sense of "a sudden blow, a violent collision" is from 1610s. The meaning "a sudden and disturbing impression on the mind" is by 1705; the sense of "feeling of being (mentally) shocked" is from 1876.

The electrical sense of "momentary stimulation of the sensory nerves and muscles caused by a sudden surge in electrical current" is by 1746. The medical sense of "condition of profound prostration caused by trauma, emotional disturbance, etc." is by 1804 (it also once meant "seizure, stroke, paralytic shock" 1794).

Shock-absorber is attested from 1906 (short form shocks attested by 1961); shock wave is from 1907. Shock troops (1917), especially selected for assault work, translates German stoßtruppen and preserves the word's original military sense. Shock therapy is from 1917; shock treatment from 1938.

"tightly, close up against," 1799, back formation from chock-full.