What is "acanthopterygii"

Acanthopterygii \Ac`an*thop`ter*yg"i*i\, n. pl. [NL., from Gr. ? thorn + ? fin, dim. fr. ? wing.] (Zo["o]l.) An order of fishes having some of the rays of the dorsal, ventral, and anal fins unarticulated and spinelike, as the perch.

Acanthopterygii (meaning "spiny finned one") is a superorder of bony fishes in the class Actinopterygii. Members of this superorder are also known as the ray-finned fishes for the characteristic sharp, bony rays in their fins; however this name is also often given to the class Actinopterygii as a whole.