button-hole n.

c. 1300, "knob or ball attached to another body," especially as used to hold together different parts of a garment by being passed through a slit or loop (surname Botouner "button-maker" attested from mid-13c.), from Old French boton "a button," originally "a bud" (12c., Modern French bouton), from bouter, boter "to thrust, strike, push," common Romanic (cognate with Spanish boton, Italian bottone), ultimately from a Germanic source, from Proto-Germanic *buttan, from PIE root *bhau- "to strike." Thus a button is, etymologically, something that pushes up, or thrusts out.

The meaning "point of the chin" is pugilistic slang, by 1921. A button as a round protuberance you depress to create an effect by closing an (electrical) circuit is attested from 1840s. Button-pusher as "deliberately annoying or provocative person" is attested by 1990 (in reference to Bill Gates, in "InfoWorld" magazine, Nov. 19). In the 1980s it meant "photographer."

Old English hol (adj.) "hollow, concave;" as a noun, "hollow place; cave; orifice; perforation," from Proto-Germanic *hulan (source also of Old Saxon, Old Frisian, Old High German hol, Middle Dutch hool, Old Norse holr, German hohl "hollow," Gothic us-hulon "to hollow out"), from PIE root *kel- (1) "to cover, conceal, save." As an adjective, it has been displaced by hollow, which in Old English was only a noun, meaning "excavated habitation of certain wild animals."

As a contemptuous word for "small dingy lodging or abode" it is attested from 1610s. Meaning "a fix, scrape, mess" is from 1760. Obscene slang use for "vulva" is implied from mid-14c. Golfing hole-in-one is from 1914; as a verbal phrase from 1913. To need (something) like a hole in the head, applied to something useless or detrimental, first recorded 1944 in entertainment publications, probably a translation of a Yiddish expression such as ich darf es vi a loch in kop.