How do we call a pair of sets $A,B$ such that there is some injection $f: A \to B$? Let $A,B$ be sets and let $f: A \to B$. If $f$ is a surjection, then we may simply write $f(A) = B$ or say in a more laborious way that $f$ maps $A$ onto $B$, to mean the same thing.
However, if $f$ is an injection, how do we abbreviate the thing that $f$ maps $A$ to $B$ in a one-one manner? I guess saying that $A$ is in injection with $B$ is misleading and hence not good, because it does not specify the "direction".

We say "$A$ injects into $B$", and may write $f: A \hookrightarrow B$.
