What does moulting mean?
Moulting is the process by which an animal sheds an old outer covering and replaces it. Birds most commonly use the term for the gradual loss and regrowth of feathers, sometimes as many are replaced at once, making the bird look temporarily less sleek or less capable of flight. Reptiles, fish, mammals, and arthropods can also moult, shedding skin, scales, hair, or an exoskeleton at particular stages of their development. As a verb, moulting describes this activity; as a noun, it names the process; and as an adjective, it describes the season, cycle, plumage, or bodily change associated with it. The word is common in British English, while molting is the standard American form. The expression can also describe a broader shedding or replacement process, although its usual application is biological. For birdwatchers and naturalists, moulting is important because plumage condition and seasonal feather loss help reveal a species' age, health, and timing of migration or breeding.
To shed and replace feathers, hair, skin, or another outer covering.
"The young eagle moults for the first time before its second winter."
Common in British English; molting is more common in American English.
The process of shedding and replacing an old outer covering, especially feathers or skin.
"Moulting temporarily reduces the bird's ability to regulate its temperature."
The process is normally treated as an uncountable noun.
Relating to or occurring during the replacement of feathers, hair, skin, or another outer covering.
"The bird has gathered some of its energy for moulting plumage."
Commonly used in specialist and descriptive contexts, especially in ornithology.
The plural is rare because the process is normally treated as uncountable.
"The annual moulting of the colony marks a period of increased vulnerability."
Moulting lets a bird replace worn feathers for the demands of flight, warmth, or the changing season.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does moulting come from?
Moulting is the present participle and gerund of the English verb moult, an inherited word with roots in Old English. The process is expressed through the ordinary English suffix -ing. The spelling with -ou- is traditional in British English, whereas American English generally uses molt and molting.
Related word forms
How moulting is actually used
Moulting is especially associated with birds replacing their feathers and with animals shedding skin or an exoskeleton. It is the usual British spelling; American English generally uses molting.