manta ray

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

• noun An extremely large pelagic tropical ray of the family Mobulidae, that feeds on plankton and small fishes. It is usually harmless but its size (up to 20 feet across and up to a ton in weight) make it dangerous if harpooned. Called also manta, sea devil and devilfish. See also cephaloptera and sea devil.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of several very large pelagic rays of the genus Manta, with winglike pectoral fins, a long tail, and two fins resembling horns that project from the head.

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

• noun extremely large pelagic tropical ray that feeds on plankton and small fishes; usually harmless but its size make it dangerous if harpooned