Definition of "collider"

collider

noun
plural colliders
1. (physics) Any of several forms of particle accelerator in which two opposing beams of particles collide.
2. (graph theory) A node in a causal graph that has at least two incoming edges.
3. (video games) A model of the shape of an object for purposes of collision detection.
  Quotations
  The race controller will check for a trigger hit between this player's collider and the start/finish line trigger, but this script has an OnTriggerEnter function to check for triggers used to force a respawn.
  2014, Jeff W. Murray, C# Game Programming Cookbook for Unity 3D, page 339