Two objects that touch each other or are related in an incidence structure are said to be incident.
In graph theory, a graph edge 
is incident to the graph
vertices 
and 
, and each of those vertices is incident
to 
.
Incident
See also
Concur, Graph Edge, Graph Vertex, Incidence Structure, Tangent CurvesExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Incident." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Incident.html