happenstance
noun [ C or U ] mainly US uk/ˈhæp.ən.stɑːns/ us/ˈhæp.ən.stæns/
（尤指出现好结果的）偶然情况，机遇
chance or a chance situation, especially one producing a good result
By (a strange) happenstance they were both in Paris at the same time. 凑巧他们俩当时都在巴黎。
Synonym: coincidence