Chambers's Twentieth Century Dictionary…
“ Chop, chop, n. the chap or jaw, generally used in pl.: a person with fat cheeks: the mouth of anything, as a cannon.—adj. Chop′-fall′en, lit. having the chop or lower jaw fallen down: cast-down: dejected. [See Chap (3) .] Chop, chop, n. in China and India, an official mark or seal: a license or passport which has been sealed. [Hind. chhāp, seal, impression.] Chopin, chop′in, n. an old French liquid measure containing nearly an English imperial pint: a Scotch measure containing about an English quart. [O. Fr. chopine, Old Dut. schoppe; Scot. chappin, Ger. schoppen, a pint.] ”
