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

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

Researchers used a method called DNA methylation to measure aging biomarkers in systems including the heart and metabolism. —Lisa Rapaport, EverydayHealth.com, 29 July 2024

To quantify these changes, the team used epigenetic clocks, tools that estimate biological age based on methylation patterns. —Brian Mastroianni, Health, 10 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