Ĭch'thy-o-saur or Ĭch'thy-o-sau'rus, n.

n. [N. Lat., from Gr. ἰχθύς, fish, and σαῦρος, lizard; Fr. ichthyosaure.] (Palæon.) An extinct carnivorous reptile of enormous size, found in the Lias formation, nearly to the close of the chalk period. It is saurian, or lizard-like, both in shape and habits. The vertebræ resemble much those of fishes; hence the name.