captain (n.)
late 14c., capitayn, "a leader, chief, one who stands at the head of others," from Old French capitaine "captain, leader," from Late Latin capitaneus "chief," noun use of adjective capitaneus "prominent, chief," from Latin caput (genitive capitis) "head" (see capitulum).

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.
captain (v.)
1590s, from captain (n.). Related: Captained; captaining.