mutation

American  

[myoo-tey-shuhn] / myuˈteɪ ʃən /

noun

1. Biology.

   1. Also called break.  a sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome.

   2. Also called sport.  an individual, species, or the like, resulting from such a departure.

2. the act or process of changing.

3. a change or alteration, as in form or nature.

4. Phonetics. umlaut.

5. Linguistics. (in Celtic languages) syntactically determined morphophonemic phenomena that affect initial sounds of words.

---

mutation British  

/ mjuːˈteɪʃən /

noun

1. the act or process of mutating; change; alteration

2. a change or alteration

3. a change in the chromosomes or genes of a cell. When this change occurs in the gametes the structure and development of the resultant offspring may be affected See also inversion

4. another word for mutant

5. a physical characteristic of an individual resulting from this type of chromosomal change

6. phonetics

   1. (in Germanic languages) another name for umlaut

   2. (in Celtic languages) a phonetic change in certain initial consonants caused by a preceding word

---

mutation Scientific  

/ myo̅o̅-tā′shən /

1. A change in the structure of the genes or chromosomes of an organism. Mutations occurring in the reproductive cells, such as an egg or sperm, can be passed from one generation to the next. Most mutations occur in junk DNA and have no discernible effects on the survivability of an organism. Of the remaining mutations, the majority have harmful effects, while a minority can increase an organism's ability to survive. A mutation that benefits a species may evolve by means of natural selection into a trait shared by some or all members of the species.

2. See Note at sickle cell anemia

---

Other Word Forms

• mutational adjective
• mutationally adverb
• nonmutational adjective
• nonmutationally adverb
• unmutational adjective

Etymology

Origin of mutation

First recorded in 1325–75; Middle English mutacio(u)n, from Latin mūtātion- (stem of mūtātiō ) “a changing”; see mutate, -ion

Explanation

A mutation is a genetic change that causes new and different characteristics, like the mutation on the dog's DNA that makes its tail shorter than its ancestors' tails. Mutation comes from the Latin word mutationem meaning "a changing." You might recognize this root in related words like mutate, mutable, and mutant. We often think of mutations as changes in an animal's genetic structure, but there are other kinds of mutations. For example, if an architect designs an award-winning building, her later designs that are similar might be called mutations of that one.

Example Sentences

They sought out genetic testing, which confirmed both children have the mutation that Regeneron’s drug targets.

From The Wall Street Journal • Apr. 23, 2026

And CML is a slower-growing form of leukemia driven by a single genetic mutation.

From The Wall Street Journal • Apr. 19, 2026

The researchers then explored whether the mutation could help repair existing myelin damage similar to what occurs in MS.

From Science Daily • Apr. 15, 2026

Mice carrying the Retsat mutation outperformed those without it in tests measuring learning, memory, and social behavior.

From Science Daily • Apr. 15, 2026

If a mutation inactivated even one function, the mold would be unable to grow—unless the missing ingredient was supplied back into the broth.

From "The Gene" by Siddhartha Mukherjee

Related Words

• alteration
• anomaly
• variation