surjection
n//sɜː(ɹ)ˈd͡ʒɛk.ʃən//surjektion
(set theory) A function for which every element of the codomain is mapped to by some element of the domain; (formally) Any function f: X\rightarrow Y for which for every y \in Y, there is at least one x \in X such that f(x) = y.