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
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
John Travis Examples of methylation in a Sentence
Recent Examples on the Web
The new atlas, published March 11 in the scientific journal Cell, details the ways in which genome structure, gene activity and methylation (a biochemical mechanism for regulating gene expression) change across eight brain regions and 36 brain cell types.
—Noah Lyons, San Diego Union-Tribune, 6 Apr. 2026
Several of the multi-cancer detection tests under development evaluate the abnormal methylation of DNA.
DNA carries the biological instructions for life.
—Juergen Eckhardt, Forbes.com, 24 Mar. 2026
The team collected skin samples from the dolphins to measure DNA methylation patterns—biochemical modifications that determine which genes are activated—in order to estimate their biological ages.
—Hasmik Kirakosyan, Scientific American, 23 Jan. 2026
Our findings also suggest that DNA methylation could help researchers understand something completely new about the brain’s response to injury that existing clinical tools cannot detect.
—Amery Treble-Barna, The Conversation, 9 Dec. 2025
See All Example Sentences for methylation
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Noah Lyons, San Diego Union-Tribune, 6 Apr. 2026
Several of the multi-cancer detection tests under development evaluate the abnormal methylation of DNA.
DNA carries the biological instructions for life.
—Juergen Eckhardt, Forbes.com, 24 Mar. 2026
The team collected skin samples from the dolphins to measure DNA methylation patterns—biochemical modifications that determine which genes are activated—in order to estimate their biological ages.
—Hasmik Kirakosyan, Scientific American, 23 Jan. 2026
Our findings also suggest that DNA methylation could help researchers understand something completely new about the brain’s response to injury that existing clinical tools cannot detect.
—Amery Treble-Barna, The Conversation, 9 Dec. 2025
See All Example Sentences for methylation
Cite this Entry
“Methylation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/methylation. Accessed 11 Apr. 2026.
Copy CitationMedical Definition
methylation
noun
meth·yl·ation
ˌmeth-ə-ˈlā-shən
: introduction of the methyl group into a chemical compound
especially
: dna methylation
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