What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Definition of reverse mutation in US English:
reverse mutation
noun
GeneticsMutation that restores a mutant phenotype or genotype to the original or normal form (the wild type); an instance of this; also called back mutation.
Origin
Early 20th century; earliest use found in Thomas Hunt Morgan (1866–1945).
