The Collaborative International Dictionary
Corporal \Cor"po*ral\ (k[^o]r"p[-o]*ral), n. [Corrupted fr. F. caporal, It. caporale, fr. capo head, chief, L. caput. See Chief, and cf. Caporal.] (Mil.) A noncommissioned officer, next below a sergeant. In the United States army he is the lowest noncommissioned officer in a company of infantry. He places and relieves sentinels.
Corporal's guard, a detachment such as would be in charge of a corporal for guard duty, etc.; hence, derisively, a very small number of persons.
Lance corporal, an assistant corporal on private's pay.
--Farrow.
Ship's corporal (Naut.), a petty officer who assists the master at arms in his various duties.
Wiktionary
n. (context nautical English) A petty officer who assists the master-at-arms in his various duties.
Usage examples of "ship's corporal".
Soon divisions down on deck were dancing with excitement as they watched the slow ascent and descent of some lumbering gurneys mate or ship's corporal.