c.1000, "part of speech," from O.Fr. part, from L. partem (nom. pars, gen. partis) "part, piece, side, share," related to L. portio "share, portion," from PIE base *per- "to assign, allot" (cf. Gk. peprotai "it has been granted," Skt. purtam "reward," Hittite parshiya- "fraction, part"). It has replaced native deal in most senses. Theatrical sense (1495) is from an actor's "share" in a performance. Meaning "the parting of the hair" is 1890, Amer.Eng.
late 13c., "to divide into parts," from O.Fr. partir "to divide, separate," from L. partire, from pars (see part (n.)). Sense of "to separate (someone from someone else)" is from early 14c.; that of "to take leave" is from early 15c. Meaning "to separate the hair" is attested from 1610s.