The Collaborative International Dictionary of English v.0.48:
Gecko \Geck"o\ (g[e^]k"[-o]), n.; pl. Geckoes (g[e^]k"[=o]z).
[Cf. F. & G. gecko; -- so called from the sound which the
animal utters.] (Zool.)
Any lizard of the family Geckonid[ae]. 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.