tetramethylammonium

noun
tet·​ra·​meth·​yl·​am·​mo·​ni·​um | \ ˌte-trə-ˌmeth-əl-ə-ˈmō-nē- əm How to pronounce tetramethylammonium (audio) \

Medical Definition of tetramethylammonium

: the quaternary ammonium ion (CH3)4N+ containing four methyl groups