Alcyonaria

from The Century Dictionary.

• An order of actinozoan corals, or, as some hold, a subclass of coralligenous Actinozoa, distinguished in this use from Zoantharia, the other subclass of Actinozoa (which contains the sea-anemones, etc.), by having pinnately fringed instead of simple tentacles, arranged around the mouth like the rays of a starfish, whence the alternative name Asteroida.
• A subclass of Anthozoa, containing the orders Stolonifera, Alcyonacea, Pseudaxonia, Axifera, Stelechotokea, and Cœnothecalia.

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

• proper noun plural (Zoöl.) One of the orders of Anthozoa. It includes the Alcyonacea, Pennatulacea, and Gorgonacea.

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

• proper noun A taxonomic subclass within the class Anthozoa — sedentary colonial cnidarians.

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

• noun corals and sea anemones having eight branches