(Chem.) A prefix or combining form (also used adjectively) indicating the presence of three methyl groups. [ 1913 Webster ]

n. [ Trimethyl- + amine. ] (Chem.) A colorless volatile alkaline liquid, N.(CH3)3, obtained from herring brine, beet roots, etc., with a characteristic herringlike odor. It is regarded as a substituted ammonia containing three methyl groups. [ 1913 Webster ]

n. (Chem.) A gaseous hydrocarbon, C3H6, isomeric with propylene and obtained from it indirectly. It is the base of a series of compounds analogous to the aromatic hydrocarbons. [ 1913 Webster ]