c.1420, "one-sided, biased," from O.Fr. parcial (14c.), from M.L. partialis "divisible, solitary, partial," from L. pars (gen. partis) "part" (see part (n.)). Sense of "not whole, incomplete" is attested from 1460 (implied in partially "incompletely"). Partiality "one-sidedness" is first recorded 1422, from M.Fr. parcialité, from M.L. partialitatem (nom. partialitas), from partialis.