chaps (n.1)youdaoicibaDictYouDict
1844, American English, short for chaparejos, from Mexican Spanish chaparreras, overalls worn to protect from chaparro (see chaparral).
chaps (n.2)youdaoicibaDictYouDict
"jaws, cheeks," from chap (n.), 1550s, of unknown origin. Hence, chap-fallen (1590s).