n. [ F. ] A process for checking the fermentation of the must of grapes. [ 1913 Webster ]
n. A chemical compound or other external influence (such as ionizing radiation) which causes mutations{ 3 }. [ PJC ]
n. the causing of a mutation or the occurrence of a mutation{ 3 }. [ PJC ]
n. the degree or measure of the ability to cause mutation{ 3 }; -- said of mutagens. [ PJC ]