Definition of "betaine" in English

noun

1. (uncountable, organic chemistry) 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⁻

2. (countable, organic chemistry) Any derivative of this compound.

3. (countable, organic chemistry, by extension) Any similar compound, based on sulfur or phosphorus etc, having an onium ion with no hydrogen atom adjacent to the anionic atom.