peristome

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Botany A fringe of toothlike appendages surrounding the mouth of a moss capsule.
2. n. Zoology The area or parts around the mouth in certain invertebrates.

Century Dictionary and Cyclopedia

1. n. In botany, the ring or fringe of delicate hairlike appendages which is observed on the rim or mouth of the capsule of a moss when the operculum is removed. These appendages are in a single row, or frequently in two rows, when the peristome is said to be double. The individuals of the outer row are called teeth, those of the inner cilia. The number of both teeth and cilia is always four or a multiple of four. See cuts under moss, cilium, 3, and Dicranum.
2. n. In zoology, mouth-parts in general; the structures or set of parts which surround the cavity of the mouth or oral opening and constitute its walls, framework, or skeleton: used chiefly of lower animals, as echinoderms, which have circular or radiate mouth-parts. Specifically — The circumoral body-wall of an echinoderm; the peristomial perisoma: the opposite of periproct. See cut under Astrophyton.

Wiktionary

1. n. botany One or two rings of tooth-like appendages surrounding the opening of the capsule of many mosses.
2. n. zoology The parts of or surrounding the mouths of numerous invertebrates.
3. n. The lip, or edge of the aperture, of a spiral shell.

GNU Webster's 1913

1. n. (Bot.) The fringe of teeth around the orifice of the capsule of mosses. It consists of 4, 8, 16, 32, or 64 teeth, and may be either single or double.
2. n. The lip, or edge of the aperture, of a spiral shell.
3. n. The membrane surrounding the mouth of an invertebrate animal.

WordNet 3.0

1. n. (botany) fringe of toothlike appendages surrounding the mouth of a moss capsule
2. n. region around the mouth in various invertebrates