chuff

chuff · adjective, adverb, noun¹

1. Middle English · inherited fromchuffe“a rustic, boor”
2. English todaychuff

15th century, dialectal, from Middle English chuffe (“a rustic, boor”), in noun sense “stupid fellow”. Adjective sense “surly, displeased” from 1832.

chuff · verb, noun²

Onomatopoeic. Compare chug and puff.

chuff · adjective, noun, verb³

1520s, in sense “swollen with fat”; circa 1860, British dialect, in sense “pleased”. Possibly related to “coarse, stupid, fat-headed” sense (see etymology 1 above). Or, perhaps a euphemistic alteration of fuck or another expletive.