Trimethylglycine is an organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 that occurs in plants as either glycine betaine or a choline-containing glycine betaine compound. Trimethylglycine was the first betaine discovered by science; originally it was simply called betaine because, in the 19th century, it was discovered in sugar beet

Sugar beet

Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B...

s. Since then, many other betaines have been discovered, and the more specific name glycine betaine distinguishes this one.
Trimethylglycine is an N-trimethylated amino acid.