Synonyms for Clash (same or very similar meaning)
WordNet sense 1 (a state of conflict between persons):
friction
WordNet sense 2 (a loud resonant repeating noise):
clang, clangor, clank, crash, clangoring, clangour
WordNet sense 3 (be incompatible; be or come into conflict):
collide, jar
WordNet sense 4 (a minor short-term fight):
brush, skirmish, encounter
From the ODE community, based on WordNet
add/edit