of, relating to, or being an injection: such that each element of the image (or range) is associated with at most one element of the preimage (or domain); inverse-deterministic
Injective, being an injection: having the property that no two elements of the domain are mapped to the same image.
Matching each member of one set with exactly one member of another set.
Involving direct communication between two people.
A personal relationship between two people.