clash
- Meet and come into violent conflict
The police clashed with rioters in the streets as they tried to restore order.
- (of colors) appear discordant or ugly when placed close to each other
The models' clothing clashed with each other, putting together colors that didn't match at all.
- Strike (cymbals) together, producing a loud discordant sound
The cymbals clashed on every beat during the height of the band's march.