[ meth-uh l-mur-kyuh-ree ]
/ ˌmɛθ əlˈmɜr kyə ri /

noun Chemistry.

any of several extremely toxic organometallic compounds, Hg(CH3)2, formed from metallic mercury by the action of microorganisms and capable of entering the food chain: used as seed disinfectants.

Origin of methylmercury

First recorded in 1915–20; methyl + mercury Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019