mutation

noun

mu·​ta·​tion myü-ˈtā-shən How to pronounce mutation (audio)
1
: a significant and basic alteration : change
2
: umlaut
3
a
: a relatively permanent change in hereditary material that involves either a change in chromosome structure or number (as in translocation, deletion, duplication, or polyploidy) or a change in the nucleotide sequence of a gene's codons (as in frameshift or missense errors) and that occurs either in germ cells or in somatic cells but with only those in germ cells being capable of perpetuation by sexual reproduction
Mutations known to cause disease have been identified in approximately 1000 genes.Alan E. Guttmacher and Francis S. Collins
also : the process of producing a mutation
Microorganisms have been used extensively to study mutationGeorge A. Wistreich et al.
b
: an individual, strain, or trait resulting from mutation
The worst E. coli bacterium, E. coli 0157:H, a mutation discovered in 1982 that has at least sixty-two subtypes, causes hemorrhagic colitis …Wayne Biddle
mutational adjective
mutationally adverb

Examples of mutation in a Sentence

The cat's short tail is the result of mutation. The condition is caused by a genetic mutation. The building is a mutation of the original design.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The disease, which typically emerges between 30 and 50 years of age, is caused by a mutation in the HTT gene, which triggers the cells to create a protein called huntingtin that can cause damage to the brain. Melissa Rudy, FOXNews.com, 8 Oct. 2025 Currently, a child who tests positive for a genetic variant might be diagnosed with a disease tied to that mutation. Santhosh Girirajan, The Conversation, 7 Oct. 2025 This signaled that the mutation was somewhere on the X chromosome, since females have two of those, and presumably one lacked the killer mutation. Beth Mole, ArsTechnica, 6 Oct. 2025 Despite a clean mammogram and sonogram months earlier, results from a genetic test revealed that Martin had inherited the BRCA2 mutation – not from her mother, who is a breast cancer survivor herself, but from her father’s side of the family. Alex Ross, PEOPLE, 1 Oct. 2025 See All Example Sentences for mutation

Word History

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of mutation was in the 14th century

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Cite this Entry

“Mutation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mutation. Accessed 9 Oct. 2025.

Kids Definition

mutation

noun
mu·​ta·​tion myü-ˈtā-shən How to pronounce mutation (audio)
1
: a basic and important change
2
a
: a permanent change in hereditary material involving either a change in the position of the genes on the chromosomes or a basic change in the chemical structure of a gene
also : the process of producing a mutation
b
: an individual, strain, or trait resulting from mutation

Medical Definition

mutation

noun
mu·​ta·​tion myü-ˈtā-shən How to pronounce mutation (audio)
1
: a relatively permanent change in hereditary material that involves either a change in chromosome structure or number (as in translocation, deletion, duplication, or polyploidy) or a change in the nucleotide sequence of a gene's codons (as in frameshift or missense errors) and occurs either in germ cells or in somatic cells but with only those in germ cells being capable of perpetuation by sexual reproduction
also : the process of producing a mutation
2
: an individual, strain, or trait resulting from mutation
mutational adjective
mutationally adverb
Last Updated: - Updated example sentences
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