As"ca*rid (&?;), n.; pl. Ascarides (&?;) or Ascarids. [NL. ascaris, fr. Gr. &?;.] (Zoöl.) A parasitic nematoid worm, espec. the roundworm, Ascaris lumbricoides, often occurring in the human intestine, and allied species found in domestic animals; also commonly applied to the pinworm (Oxyuris), often troublesome to children and aged persons.