A terminator sequence is a segment of DNA that signals the end of a gene or other genetic element. Synonyms for a terminator sequence include stop codon, terminator codon, and end codon. These terms all refer to the same sequence of three nucleotides that signals the end of a genetic message. Another synonym is polyadenylation signal, which is a sequence of nucleotides that signals the addition of a series of adenine residues to the 3' end of a messenger RNA molecule, another process that terminates gene expression. Overall, terminator sequences play an essential role in regulating gene expression and ensuring that genetic messages are accurately and efficiently transcribed.