methylmercury

noun

meth·​yl·​mer·​cury ˌme-thəl-ˈmər-kyə-rē 

-ˈmər-k(ə-)rē

: any of various toxic compounds of mercury containing the complex CH₃Hg− that often occur as pollutants which accumulate in living organisms (such as fish) especially in higher levels of a food chain

Examples of methylmercury in a Sentence

Recent Examples on the Web

Because microorganisms in water turn regular mercury into methylmercury, a toxic chemical form that binds tightly to fish tissue, the heavy metal accumulates to higher levels in aquatic animals. — Sandee Lamotte, CNN Money, 2 Oct. 2026

Salmon and its skin can contain low levels of methylmercury, a toxin that can be passed from the mother to her child. — Kait Hanson, Southern Living, 18 Sep. 2026

This methylmercury bioaccumulated in Minamata Bay’s fish and shellfish. — Encyclopedia Britannica, 3 Sep. 2026

This decision was based on what levels were considered safe for methylmercury (the kind in fish), which is structurally very different from the ethylmercury found in thimerosal. — Lauren Gelman, Parents, 21 Nov. 2025

Word History

First Known Use

1915, in the meaning defined above

Rhymes for methylmercury

• mercury

Medical Definition

methylmercury

noun

meth·​yl·​mer·​cury

ˌmeth-əl-ˈmər-kyə-rē, British also ˌmē-ˌthīl-

plural methylmercuries

: any of various toxic compounds of mercury containing the complex CH₃Hg− that often occur as pollutants formed as industrial by-products or pesticide residues, tend to accumulate in living organisms (as fish) especially in higher levels of a food chain, are rapidly and easily absorbed through the human intestinal wall, and cause neurological dysfunction in humans see minamata disease