a ribonucleotide triplet signaling the termination of the translation of a protein chain
is any one of three triplets (UAG, UAA, UGA) that cause termination of protein synthesis. (UAG is known as amber UAA as ochre.)
One of the mRNA sequences (UAA, UAG, UGA) that signals the termination of translation codon for which no normal tRNA molecule exists. The presence of a nonsense codon causes termination of translation (ending polypeptide chain synthesis). There are three nonsense codons are called amber(UAG) ochre(UAA) and opal(UGA).