champ (n.) Look up champ at
1868, American English abbreviation of champion (n.).
champ (v.) Look up champ at
"to chew noisily," 1520s, probably echoic; OED suggests a connection with jam (v.). Earlier also cham, chamb, etc. To champ on (or at) the bit, as an eager horse will, is attested in figurative sense by 1640s. Related: Champed; champing. As a noun in this sense, attested from c. 1600.