happenstance

1. N-UNCOUNT If you say that something happened by happenstance, you mean that it happened because of certain circumstances, although it was not planned by anyone. 偶然情况; 巧合[书面] [also 'a' N, oft 'by' N]

I came to live at the farm by happenstance. 我到这个农场来生活纯属偶然。