Gecko :: Gecko (n.) Any lizard of the family Geckonidae. The geckoes are small, carnivorous, mostly nocturnal animals with large eyes and vertical, elliptical pupils. Their toes are generally expanded, and furnished with adhesive disks, by which they can run over walls and ceilings. They are numerous in warm countries, and a few species are found in Europe and the United States. See Wall gecko, Fanfoot..