- biceps
- 1630s (adj.), from Latin biceps "having two parts," literally "two-headed," from bis "double" (see bis-) + -ceps comb. form of caput "head" (see capitulum). As a noun meaning "biceps muscle," from 1640s, so called for its structure. Despite the -s, it is singular, and classicists insist there is no such word as bicep.
