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See more synonyms for moult on Thesaurus.com
verb (used with or without object), noun British.
  1. molt.
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verb (used without object)
  1. (of birds, insects, reptiles, etc.) to cast or shed the feathers, skin, or the like, that will be replaced by a new growth.
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verb (used with object)
  1. to cast or shed (feathers, skin, etc.) in the process of renewal.
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  1. an act, process, or an instance of molting.
  2. something that is dropped in molting.
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Also especially British, moult.

Origin of molt

1300–50; earlier mout (with intrusive -l-; cf. fault, assault), Middle English mouten, Old English -mūtian to change (in bi-mūtian to exchange for) < Latin mūtāre to change; see mutate
Related formsmolt·er, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for moult

Contemporary Examples

Historical Examples

  • You always choose February to moult in, and you will have to be feathered down there.

    Love and Lucy

    Maurice Henry Hewlett

  • Jack was caught two or three times, and Dan and Moult as often.

    The Innocents Abroad

    Mark Twain (Samuel Clemens)

  • Head black (with some white after the moult at Christmas), abdomen black.

    Indian Birds

    Douglas Dewar

  • From the French muer, and the Latin mutare, to change, of hawks to moult.

    The Master of Game

    Second Duke of York, Edward

  • During a moult the cuticle of the head is cast separately from that of the body.

British Dictionary definitions for moult


US molt

  1. (of birds, mammals, reptiles, and arthropods) to shed (feathers, hair, skin, or cuticle)
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  1. the periodic process of moultingSee also ecdysis
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Derived Formsmoulter or US molter, noun

Word Origin

C14 mouten, from Old English mūtian, as in bimūtian to exchange for, from Latin mūtāre to change


verb, noun
  1. the usual US spelling of moult
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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

Word Origin and History for moult

see molt.

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also moult, mid-14c., mouten, of feathers, "to be shed," from Old English *mutian "to change" (cf. bemutian "to exchange"), from Latin mutare "to change" (see mutable). Transitive sense, of birds, "to shed feathers" is first attested 1520s. With parasitic -l-, late 16c., on model of fault, etc. Related: Molted, moulted; molting, moulting. As a noun from 1815.

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Online Etymology Dictionary, © 2010 Douglas Harper

moult in Medicine


  1. To shed periodically part or all of a coat or an outer covering, such as feathers, cuticle, or skin, which is then replaced by a new growth.
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  1. The act or process of molting.
  2. The material cast off during molting.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

moult in Science


  1. To shed an outer covering, such as skin or feathers, for replacement by a new growth. Many snakes, birds, and arthropods molt.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.