A local sink is a node of a Directed Graph with no exiting edges, also called a Terminal (Borowski and Borwein 1991, p. 401). A (global) sink is a node in a Directed Graph which is reached by all directed edges (Harary 1994, p. 201).
See also Directed Graph, Network, Source
References
Borowski, E. J. and Borwein, J. M. (Eds.). The HarperCollins Dictionary of Mathematics.
New York: HarperCollins, 1991.
Harary, F. Graph Theory. Reading, MA: Addison-Wesley, 1994.