A mutation that restores, partially or completely, the loss of function caused by another mutation. Many suppressor mutations are in genes encoding a transfer RNA species; the altered tRNA can recognise the original mutant codon and, during translation, insert an acceptable substitute amino acid into the polypeptide.

A mutation in one gene that reverses the effect of ("suppresses") a mutation in a second gene.

A mutation that reverses the phenotypic effect of a second mutation. Suppressor mutations are frequently used to identify genes encoding interacting proteins.

A secondary mutation that restores function lost due to mutation at another site.

A mutation that counteracts the effects of another mutation. A suppressor maps at a different site from the mutation that it counteracts, either within the same gene or at a more distant locus. Different suppressors act in different ways.