collisioncol·li·sion /kəˈlɪʒən/ noun [countableC, uncountableU]1INSURANCEwhen a vehicle hits another vehicle or object, causing damageHis car was in collision with another vehicle.
All aircraft are now fitted with collision-avoidance equipment.
2on a collision course (with) if two groups are on a collision course, they are very likely to have a serious disagreement at some time in the futureThis latest announcement may put the nation’s largest cable operators on a collision course with telephone companies.