1590s, "action of killing one's mother," from French matricide, from Latin matricida "mother-killer," and matricidium "mother-killing," from comb. form of mater "mother" (see mother, n.1) + -cida "killer," and -cidium "a killing," from caedere "to slay" (see -cide). Meaning "one who kills his mother" is 1630s. Related: Matricidal (adj.). Old English had moðorslaga "matricide, mother-slayer."