Smash in Definition 1 of 3Pro Tip 1/3Violence Implied Using 'smash in' suggests aggressive behavior and destruction. During the riot, the mob smashed in storefronts. Pro Tip 2/3Criminal Activity 'Smash in' often appears in narratives involving theft or vandalism. The thief was caught on camera smashing in the car window. Pro Tip 3/3Physical Force This phrase emphasizes the physical force used to break something. The firefighter had to smash in the door to rescue the trapped people.