1.NounAny of a class of organic compounds consisting of various numbers of amino acids in which the amine of one is reacted with the carboxylic acid of the next to form an amide bond. Such molecules joined into polypeptides and proteins constitute crucial components of living organisms.
2.NounThe peptide bond itself.
3.NounPerformance-enhancing drugs that contain such molecules, especially particular ones (often synthetically produced) that are claimed by their sellers to bestow amazing health benefits.