a codon that stops the synthesis of a protein molecule.
Also called chain termination codon.
stop codon in Science
(stŏp) Any of three codons in a molecule of messenger RNA that do not code for an amino acid and thereby signal the termination of the synthesis of a protein. The three stop codons are UAA, UAG, and UGA, where U is uracil, A is adenine, and G is guanine. Also called termination codon.