A sweet, crystalline compound (not an alkaloid), trimethylammoniumacetate, found in sugar beet and similar plants, sometimes used to treat muscular degeneracy; the zwitterion (CH3)3N+CH2COO-
Any derivative of this compound.
(by extension) Any similar compound, based on sulfur or phosphorus etc, having an onium ion with no hydrogen atom adjacent to the anionic atom.