The Collaborative International Dictionary of English v.0.48:

Trimethylamine \Tri*meth`yl*am"ine\, 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]