merosome

from The Century Dictionary.

• noun In zoöl., one of the definite successive parts or segments of which the body is composed; ametamere; a somite. Thus, one of the rays of a starfish, or one of the rings of a worm or crustacean, is a merosome.

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

• noun (Zoöl.) One of the serial segments, or metameres, of which the bodies of vertebrate and articulate animals are composed.

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

• noun biology Any of the segments of a segmented animal