meth·​yl·​a·​tion ˌme-thə-ˈlā-shən How to pronounce methylation (audio)
: 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 can be done through chemical processes methylation, which turns genes on, or demethylation, which turns genes off. Allison Deangelis, STAT, 4 Jan. 2024 Although methylation patterns and how they are regulated remain poorly understood, studies have shown that methylation decreases with age, with centenarians having the least. Bárbara Pinho, Discover Magazine, 17 Feb. 2021 And although most methyl-seq technologies haven't yet been able to differentiate between different forms of methylation, newer technologies have allowed researchers to begin to tease apart how different modifications can cause differences in the biology. Demaris Mills, Forbes, 24 June 2022 The researchers said the pattern of methylation suggested that the same genes may be involved in both processes. James Gorman, Star Tribune, 14 Nov. 2020 It is controlled by methylation changes to CpG islands on promoter regions, the remodeling of chromatin using histone modifications, and the alteration of gene expression through non-coding RNA expression. Salvatore Viscomi, Forbes, 22 Mar. 2023 The addition of methyl tags to DNA bases, called methylation, is an epigenetic change that allows some genes to be transcribed while others are not. Veronique Greenwood, Discover Magazine, 12 July 2011 The researchers found that the pattern of methylation suggested that the same genes may be involved in both processes. James Gorman, New York Times, 9 Nov. 2020 Grail chose to focus entirely on methylation, a chemical change to the DNA, not the code itself. Matthew Herper, STAT, 19 May 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'methylation.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1855, in the meaning defined above

Time Traveler
The first known use of methylation was in 1855

Dictionary Entries Near methylation

Cite this Entry

“Methylation.” Dictionary, Merriam-Webster, Accessed 18 Apr. 2024.

Medical Definition


meth·​yl·​ation ˌmeth-ə-ˈlā-shən How to pronounce methylation (audio)
: introduction of the methyl group into a chemical compound
especially : dna methylation
methylate transitive verb
methylated; methylating
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