flukey
['flu:ki]
adj. 侥幸的, 幸中的, 不可靠的, 变化无常的(尤指风)
例句与用法:
His failure in history examination was a mere fluke.
他历史考试没能及格纯属偶然。
She is not usually good at tennis; that winning stroke was a fluke.
她平时网球打得并不好,那取胜的一击不过是侥幸而已。