corporal (n.) Look up corporal at Dictionary.com
1570s, from M.Fr. corporal, from It. caporale "a corporal," from capo "chief, head," from L. caput "head" (see head). So called because he was in charge of a body of troops. Perhaps infl. by It. corpo, from L. corps "body." Or corps may be the source and caput the influence, as the OED suggests. Corporal punishment "punishment of the body" (as opposed to fine or loss of rank or privilege) is from 1580s.
corporal (adj.) Look up corporal at Dictionary.com
"of or belonging to the body," late 14c., from O.Fr. corporal, from L. corporalis, from corpus (gen. corporis) "body" (see corps). Corporal punishment (1580s) is that inflicted on the body as opposed to fines or loss of rank.