Reptilian (adjective)

1. Of, relating to, or characteristic of reptiles.
2. Having the cold and unfeeling qualities associated with reptiles.
3. Resembling reptiles in appearance or behavior.

Origin:

Derived from the latin word 'reptilis' meaning 'creeping' or 'crawling', the word has been in use since the 17th century.

Examples:

1. The scientist studied the anatomy, physiology, and behavior of the reptilian species in the ecosystem.
2. The villain's reptilian eyes and smile gave him a sinister and menacing appearance.
3. The actor's performance as the reptilian monster was praised for its realism and creativity.
4. The dinosaur exhibit at the museum featured life-sized models of various reptilian species from the Jurassic period.
5. The psychologist attributed the patient's anger and violence to a reptilian part of the brain that governs survival and aggression.