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

In blood and saliva, mutations increase with age, but in oocytes, harmful mutations with high frequencies were rarer and more evenly distributed elsewhere, suggesting a form of natural quality control. —Melissa Fleur Afshar, MSNBC Newsweek, 3 Dec. 2025

Scientists gear up for this global sweep months in advance, working to figure out what mutations have popped up and using them to craft the right mix so that the flu shot — which usually becomes available in August or September — can help protect you. —The Washington Post, San Diego Union-Tribune, 2 Dec. 2025

New variation emerges from reshuffling segments of DNA in sperm and egg cells, and from copying errors known as mutations. —F.d. Flam, Mercury News, 26 Nov. 2025

In some rare cases, people can inherit mutations that cause AML to run in families, with recent research suggesting that these cases may be more common than previously thought, Chung noted. —Melissa Rudy, FOXNews.com, 25 Nov. 2025

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