Webster's Revised Unabridged Dictionary · 1913

Betaine

Betaine ({not transcribed}) , noun

[From beta, generic name of the beet.]

(Chemistry) 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.