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

For the study, researchers used DNA methylation markers (which indicate biological age) to analyze blood samples from children with or without MS. —Ashley MacKin Solomon, San Diego Union-Tribune, 10 June 2025

Yet, the majority of aging biomarkers and biological age clocks (think epigenetic methylation models) have been designed around male physiology. —Ximena Araya-Fischel, Forbes.com, 29 May 2025

This approach captures changes in gene expression, DNA structure and methylation—allowing clinicians to track how cancer develops and responds to treatment over time. —Alexis Kayser, MSNBC Newsweek, 1 May 2025

However, as part of Investigation Discovery’s The Curious Case of Natalia Grace, Natalia took a DNA methylation test, which determines age by how much one’s DNA has changed over time. —Bethy Squires, Vulture, 19 Mar. 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