Definition of "endpoint"

Either of the two points at the ends of a line segment.  examples

(biology, medicine) A defined occurrence during the observation period of an experiment or study.

(chemistry) The stage in a titration at which a change in the colour of an indicator indicates that no more titrant should be added.  examples

(networking, telecommunications) The entity at one end of a connection.  examples

(programming) Part of a system that serves as a hook, allowing third-party code to intercept and modify behaviour at that point.  examples

(mathematics) Either of the two nodes of a graph of degree 1.  examples