a small group of chemical units, consisting of a sequence of three nucleotides, that codes the incorporation of a specific small group of amino acids into a protein molecule during the synthesis of the protein; codons are present in DNA and RNA
Origin:
cod(e) + -on, as in proton
See codon in American Heritage Dictionary 4
noun
A sequence of three adjacent nucleotides constituting the genetic code that determines the insertion of a specific amino acid in a polypeptide chain during protein synthesis or the signal to stop protein synthesis.