A suppressor mutation, also known as a compensatory mutation or second-site mutation, occurs when a mutant gene that causes a genetic defect is modified by a second mutation, resulting in the restoration of normal gene function. There are several synonyms for suppressor mutation, including revertant mutation, suppressor allele, back mutation, correction mutation, and rescuing mutation. These terms all refer to mutations that correct or offset the effects of a previous mutation. Suppressors can occur within the same gene or in a different gene that interacts with the original gene, and they can be spontaneous or induced by environmental factors or treatment with mutagens. The study of suppressor mutations has important implications for understanding genetic diseases and developing therapeutic approaches.