Ich`thy*o*sau"rus (?), n.; pl. Ichthyosauri (#). [NL., fr. Gr. 'ichqy`s, -y`os, a fish + say^ros a lizard.] Paleon.
An extinct genus of marine reptiles; -- so named from their short, biconcave vertebrae, resembling those of fishes. Several species, varying in length from ten to thirty feet, are known from the Liassic, Oolitic, and Cretaceous formations.
© Webster 1913.