zona

from The Century Dictionary.

• noun In anatomy, a zone, belt, or girdle, or part likened to a zone: chiefly used in human anatomy.
• noun Herpes zoster (which see, under herpes).

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

• noun A zone or band; a layer.
• noun (Biol.) The zona radiata.
• noun (Biol.) a radiately striated membrane situated next the yolk of an ovum, or separated from it by a very delicate membrane only.

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

• noun A species of silverside fish (Atheriniformes), Bedotia geayi, from Madagascar, also called red-tailed silverside.
• noun A zone or band; a layer.

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

• noun (anatomy) any encircling or beltlike structure