noun

• (properly) A reptile of the suborder Sauria.
  "I took heart, however, as I recalled a conversation between Challenger and Summerlee upon the habits of the great saurians."
• (popularly, especially science fiction) Any large reptilian animal, including crocodiles and reptilian aliens.
  "After dinner we all went on deck and watched the unfamiliar scenes of a Capronian night--that is, all but von Schoenvorts. There was less to see than to hear. From the great inland lake behind us came the hissing and the screaming of countless saurians. Above us we heard the flap of giant wings, while from the shore rose the multitudinous voices of a tropical jungle--of a warm, damp atmosphere such as must have enveloped the entire earth during the Palezoic and Mesozoic eras."
• (figuratively) A lizardlike person.
  "He was one of the very few larger saurians in the émigré marshes."

adj

• (zoology) Of or related to the members of the suborder Sauria.
• (figuratively) Synonym of lizardlike or reptilian.