Old English hond, hand "hand; side; power, control, possession," from Proto-Germanic *khanduz (cf. Old Saxon, Old Frisian, Dutch, German hand, Old Norse hönd, Gothic handus). The original Old English plural handa was superseded in Middle English by handen, later hands.
Meaning "person who does something with his hands" is from 1580s, hence "hired workman" (1630s) and "sailor in a ship's crew" (1660s). Clock and watch sense is from 1570s. Meaning "round of applause" is from 1838. The linear measure of 4 inches (originally 3) is from 1560s, now used only in giving the height of horses. The meaning "playing cards held in one player's hand" is from 1620s; that of "a round at a card game" is from 1620s.