Source : Webster's Revised Unabridged Dictionary (1913)

Betaine \Be"ta*ine\, n. [From beta, generic name of the beet.]
   (Chem.)
   A nitrogenous base, {C5H11NO2}, produced artificially, and
   also occurring naturally in beet-root molasses and its
   residues, from which it is extracted as a white crystalline
   substance; -- called also {lycine} and {oxyneurine}. It has a
   sweetish taste.

Source : WordNet®

betaine
     n : a sweet tasting alkaloid that occurs in sugar beets