Old English team "descendant, family, race, line; child-bearing, brood; company, band; set of draft animals yoked together," from Proto-Germanic *tau(h)maz (source also of Old Norse taumr, Old Frisian tam "bridle; progeny, line of descent," Dutch toom, Old High German zoum, German Zaum "bridle"), probably literally "that which draws," from PIE *douk-mo-, from root *deuk- "to lead."
Applied in Old English to groups of persons working together for some purpose, especially "group of people acting together to bring suit;" modern sense of "persons associated in some joint action" is from 1520s. Team spirit is recorded from 1928. Team player attested from 1886, originally in baseball.
1550s, "to harness beasts in a team," from team (n.). From 1841 as "drive a team." The meaning "to come together as a team" (usually with up) is attested from 1932. Transitive sense "to use (something) in conjunction" (with something else) is from 1948. Related: Teamed; teaming. The Old English verb, teaman, tieman, is attested only in the sense "bring forth, beget, engender, propagate."