The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of numerous radially symmetrical marine invertebrates of the phylum Echinodermata, which includes the starfishes, sea urchins, and sea cucumbers, having an internal calcareous skeleton and often covered with spines.
n. Any member of the Echinodermata, a group of radially symmetric, spiny-skinned marine animals. Examples of echinoderms include seastars, sea urchins, sea cucumbers, crinoids, and sand dollars.
the GNU version of the Collaborative International Dictionary of English
n. One of the Echinodermata.
The Century Dictionary and Cyclopedia
Having a prickly covering; echinodermatous.
n. Any one of the Echinodermata.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. marine invertebrates with tube feet and five-part radially symmetrical bodies
Word Usage
"The echinoderm was the first to latch on, gradually growing as it sat on the shell, but sometime later a bryozoan larvae also took up residence there."