fess (n.) Look up fess at Dictionary.com
wide horizontal band across an escutcheon, late 15c., from Old French faisce, from Latin fascia "a band" (see fasces).
fess (v.) Look up fess at Dictionary.com
shortened form of confess, attested by 1840, American English. With up (adv.) from 1930. Related: Fessed; fesses; fessing.