Heterosis, hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring. The adjective derived from heterosis is heterotic.
An offspring exhibits heterosis if its traits are enhanced (which is often defined in terms of evolutionary fitness) as a result of mixing the genetic contributions of its parents. These effects can be due to Mendelian or non-Mendelian inheritance.
Read more about Heterosis: Definitions, Controversy, Genetic Basis of Heterosis, In Plants, Hybrid Livestock, Humans, Molecular Bases of Heterosis