A knockout mutation is a genetic alteration that results in the total loss of function of a particular gene. Synonyms for this term include loss-of-function mutation, null mutation or inactivation mutation. Other terms that can describe the same phenomenon are gene disruption, gene knockout, gene deletion or gene silencing. These terms are often used interchangeably, but each has a slightly different meaning depending on the context. Loss-of-function mutations can be used for a variety of purposes in research to help understand the role that specific genes play in essential biological processes. It is important to have a working understanding of these synonyms when reading scientific articles or communicating with colleagues in the field.