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 mutation George 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
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.
With real-time data missing, the broader community is left guessing about which strains are circulating in the United States right now — an especially concerning blind spot given the threat of H5N1 and the constant mutation of seasonal flu viruses. Richard Hughes Iv, Baltimore Sun, 19 Mar. 2025 The study, on dog domestication, found that dogs possess two mutations of a gene known as melanocortin 2 receptor (MC2R), which is linked to the production of cortisol, a hormone released during moments of fear or anxiety. Raja Krishnamoorthi, Newsweek, 13 Mar. 2025 Tempranillo Blanco, a naturally occurring mutation of Tempranillo that was first discovered in 1988 and allowed into production in 2007, is second most populous and accounts for 13 percent of vineyards. Jeremy Repanich, Robb Report, 10 Mar. 2025 Subscribe to hear this story On a special episode (first released on February 27, 2025) of The Excerpt podcast: As bird flu, also known as H5N1, continues to spread across the country, experts are concerned about the potential for undetected transfer and mutations. Dana Taylor, USA TODAY, 3 Mar. 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

Browse Nearby Words

Cite this Entry

“Mutation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mutation. Accessed 25 Mar. 2025.

Kids Definition

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

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
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