Smash up Definition 1 of 3Pro Tip 1/3Violent Action Indicates a strong, possibly aggressive force used to destroy. The protesters got angry and smashed up the storefronts. Pro Tip 2/3Total Destruction Implies that the item is damaged beyond repair, not just slightly broken. After the hailstorm, the greenhouse was completely smashed up. Pro Tip 3/3Emotional Response Can suggest anger or frustration led to the action of destroying something. In a fit of rage, he smashed up all the plates.