(transport) A collision where the front ends of two vehicles (such as ships, trains, cars, planes, etc.) hit each other, as opposed to a side-collision or rear-end collision.

(chemistry) Any theory that relates collisions among particles to reaction rate; reaction rate depends on such factors as concentration, surface area, temperature, stirring, and the presence of either a catalyst or an inhibitor.

(physics) the interaction between two moving electric charges at close range

(nautical) A large square of canvas, treated with a sealing agent and attached to lines at each corner; hauled over a damaged part of the hull to limit the inflow of water

(nautical) A strong, watertight transverse bulkhead in the fore part of a ship to prevent water flowing aft in the event of a collision

plural of head-on collision

(software compilation) An error caused by two source code elements (such as variables or functions) having the same name as each other.

plural of Coulomb collision

plural of collision course

Used other than figuratively or idiomatically: see on, a, collision course.