Bill"fish` (-f&ibreve;sh`), n. (Zoöl.) A name applied to several distinct fishes: (a) The garfish (Tylosurus, or Belone, longirostris) and allied species. (b) The saury, a slender fish of the Atlantic coast (Scomberesox saurus). (c) The Tetrapturus albidus, a large oceanic species related to the swordfish; the spearfish. (d) The American fresh-water garpike (Lepidosteus osseus).