Protein

n. essential organic compound composed of 20 or more amino acids joined by peptide bonds

Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by a gene and encoded in the genetic code. Although this genetic code specifies 20 "standard" amino acids, the residues in a protein are often chemically altered in post-translational modification: either before the protein can function in the cell, or as part of control mechanisms. Proteins can also work together to achieve a particular function, and they often associate to form stable complexes.
See more at Wikipedia.org...

Protein /pro·tein/ any of a group of complex organic compounds containing carbon, hydrogen, oxygen, nitrogen, and sulfur. [more]Protein - Community and Resources

Noun
1. any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"
(hypernym) macromolecule, supermolecule
(hyponym) capsid
(substance-holonym) meat
(substance-meronym) amino acid, aminoalkanoic acid

n. protein, essential organic compound composed of 20 or more amino acids joined by peptide bonds