amino acid

Meaning

1. Any organic compound containing both an amino and a carboxylic acid functional group.
2. Any of the twenty naturally occurring α-amino acids (having the amino, and carboxylic acid groups on the same carbon atom), and a variety of side chains, that combine, via peptide bonds, to form proteins.

Etymology

See amine and acid. Likely a calque of German Aminosäure, which is attested earlier.