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. 偶然情況; 巧郃[書麪] [also 'a' N, oft 'by' N]

I came to live at the farm by happenstance. 我到這個辳場來生活純屬偶然。