Origin: 1325–75; Middle English capitain < Anglo-French capitain, captayn < Late Latin capitāneus chief, equivalent to capit- (stem of caput) head + -ān(us) -an + -eus-eous
late 14c., "one who stands at the head of others," from O.Fr. capitaine, from L.L. capitaneus "chief," n. use of adj. capitaneus "prominent, chief," from L. caput (gen. capitis) "head" (see head). Military sense of "officer who commands a company" (rank between major and lieutenant)
is from 1560s; naval sense of "officer who commands a man-of-war" is from 1550s, extended to "master or commander of a vessel of any kind" by 1704. Sporting sense is first recorded 1823.