1an instance of one moving object or person striking violently against another:a mid-air collision between two aircraft [mass noun]:his car was in collision with a lorry
a conflict between opposing ideas, interests, or factions:a collision of two diverse cultures and languages
2 Computing an instance of two or more records being assigned the same identifier or location in memory.
an instance of simultaneous transmission by more than one node of a network.
on (a) collision course
adopting an approach that is certain to lead to conflict with another person or group:nurses are on a collision course with the government