c. 1300, "attendant in a noble household," of unknown origin, perhaps a contraction of Old English iunge man "young man," or from an unrecorded Old English *geaman, equivalent of Old Frisian gaman "villager," from Old English -gea "district, region, village," cognate with Old Frisian ga, ge, German Gau, Gothic gawi, from Proto-Germanic *gaujan.
Sense of "commoner who cultivates his land" is recorded from early 15c.; also the third order of fighting men (late 14c., below knights and squires, above knaves), hence yeomen's service "good, efficient service" (c. 1600). Meaning "naval petty officer in charge of supplies" is first attested 1660s. Yeowoman first recorded 1892: "Then I am yeo-woman O the clumsy word!" [Tennyson, "The Foresters"]