Synonyms for Offbeat (same or very similar meaning)
WordNet sense 1 (an unaccented beat (especially the last beat of a measure)):
upbeatWordNet sense 2 (informal terms; strikingly unconventional):
far-out, quirky, way-outWordNet sense 3 (not conventional or conformist):
unconventionalFrom the ODE community, based on WordNetadd/edit