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[per-uh-stohm] /ˈpɛr əˌstoʊm/
Botany. the one or two circles of small, pointed, toothlike appendages around the orifice of a capsule or urn of mosses, appearing when the lid is removed.
Zoology. any of various structures or sets of parts that surround or form the walls of a mouth or mouthlike opening.
Origin of peristome
From the New Latin word peristoma, dating back to 1790-1800. See peri-, -stome
Related forms
peristomal, peristomatic
[per-uh-stuh-mat-ik] /ˌpɛr ə stəˈmæt ɪk/ (Show IPA),
peristomial, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for peristome


a fringe of pointed teeth surrounding the opening of a moss capsule
any of various parts surrounding the mouth of invertebrates, such as echinoderms and earthworms, and of protozoans
Derived Forms
peristomal, peristomial, adjective
Word Origin
C18: from New Latin peristoma, from peri- + Greek stoma mouth
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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peristome in Science
  1. A fringe of toothlike appendages surrounding the mouth of the spore capsule of some mosses. The teeth unfold under damp conditions and curl up under dry conditions to disperse spores gradually.

  2. The area or parts around the mouth in certain invertebrates, such as the echinoderms.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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