What is "tetramethylammonium hydroxide"

n. (context organic compound English) The quaternary ammonium base (CH₃)₄N⁺ OH^-

Tetramethylammonium hydroxide (TMAH or TMAOH) is a quaternary ammonium salt with the molecular formula N(CH) OH. It is commonly encountered as concentrated solutions in water or methanol. The solid and solutions are colorless, or yellowish if impure. Although TMAH has virtually no odor when pure, samples often have a strongly fishy smell from the trimethylamine which is a common impurity. TMAH has numerous and diverse industrial and research applications (see below).