methylation

noun

meth·​yl·​a·​tion ˌme-thə-ˈlā-shən 

: the introduction of a methyl radical into a substance

The methylation of metals (that is, the substitution of a metal atom for the hydrogen atom of the hydroxyl group of a methyl alcohol molecule) can result in the metal's becoming volatile.

—Corale L. Brierley

especially : dna methylation

As cells begin to specialize into adult tissues, methylation seems to inactivate genes that are no longer needed.

—John Travis

Examples of methylation in a Sentence

Recent Examples on the Web

During methylation, a methyl group in the epigenome turns genes off. — Tad Friend, New Yorker, 4 Aug. 2025

Epigenetic changes, such as methylation of genes involved in the immune response, were also documented. — Scott E. Solomon, STAT, 22 Apr. 2026

Each test measured a process called methylation, which is where a methyl molecule attaches to a DNA building block called a nucleotide. — Tom Gavin, EverydayHealth.com, 12 May 2026

But perhaps the strongest evidence of her secret to longevity came through her epigenetic clock markers, which tell the story of biological age through DNA methylation patterns. — New Atlas, 24 Sep. 2025

Word History

First Known Use

1855, in the meaning defined above

Phrases Containing methylation

• DNA methylation

Rhymes for methylation

• abdication
• aberration
• abjuration
• abnegation
• abrogation
• acceptation
• acclamation
• acclimation
• accusation
• activation
• actuation
• acylation

Medical Definition

methylation

noun

meth·​yl·​ation ˌmeth-ə-ˈlā-shən 

: introduction of the methyl group into a chemical compound

especially : dna methylation

methylate

ˈmeth-ə-ˌlāt 

transitive verb

methylated; methylating