Treated as plural. A class (or subclass) of bony fishes comprising the ray-finned fishes, characterized by having hard and spiny rays in the dorsal fins.
((n. pl.) An order of fishes having some of the rays of
the dorsal, ventral, and anal fins unarticulated and spinelike, as the
perch.)
Origin:
Mid 18th century; earliest use found in John Hill (bap. 1714, d. 1775), physician and actor. From post-classical Latin Acanthopterygii, plural noun (P. Artedi Ichthyologia 86) from acantho- + -pterygii.