 Epimorphism

An epimorphism $e:A\to B$ is right-cancellative: $fe=ge$ implies $f=g$. In the Category of sets and in abelian groups, epimorphisms are precisely the surjective homomorphisms.

In the context of mathematics, particularly in category theory and algebra, an epimorphism is a morphism (or map) between two objects that generalizes the notion of an "onto" function in set theory.