Definition:Directed Graph/Arc/Endvertex

Definition
Let $D = \left({V, E}\right)$ be a digraph.

Let $e = u v$ be an arc of $D$, that is, $e \in E$.

The endvertices of $e$ are the vertices $u$ and $v$.

Also known as
The endvertices of an arc $e$ are also known as the endpoints of $e$.