mutation

noun

mu·​ta·​tion myü-ˈtā-shən 

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

mutational

myü-ˈtā-sh(ə-)nəl 

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

Doctors acknowledge this year’s flu jab might not be a perfect match for this new mutation, but stress the vaccine can still help prevent serious symptoms. —Lisa Gutierrez updated January 8, Kansas City Star, 8 Jan. 2026

To stay ahead of potential future COVID-19 mutations, scientists at UC San Diego in La Jolla and international collaborators set their sights on the past. —Noah Lyons, San Diego Union-Tribune, 7 Jan. 2026

Americans are being urged to be extra vigilant this winter, as a suite of influenza A mutations has created a dominant virus strain that's spreading more rapidly and evading our natural and therapeutic abilities to fight infection. —New Atlas, 5 Jan. 2026

The mutation, known as Subclade K, now makes up most of the flu viruses detected in the United States. —Marvin Hurst, CBS News, 3 Jan. 2026

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing mutation

• back mutation
• gene mutation
• genetic mutation
• point mutation

Rhymes for mutation

• ablation
• bination
• carnation
• cassation
• castration
• causation
• centration
• cessation
• cetacean
• chelation
• citation
• collation

Kids Definition

mutation

noun

mu·​ta·​tion myü-ˈtā-shən 

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 

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

-shnəl, -shən-ᵊl 

adjective

mutationally

-ē 

adverb