happenstance hap·pens·tance UK/ˈhap(ə)nˌstɑːns/ US/ˈhæpənˌstæns/ uncommon noun 1. an event that might have been arranged although it was really accidental Synonymscoincidence Related words Broader terms accident WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved.