elasmobranchii

from The Century Dictionary.

• A class, subclass, or order of fishes, otherwise known as Chondropterygii and Selachii, including the sharks and skates: so named from the lamellar branchiæ, or plate-like gills.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) A subclass of fishes, comprising the sharks, the rays, and the Chimæra. The skeleton is mainly cartilaginous.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun sharks; rays; dogfishes; skates