fortuitous
词根词缀：
fortuitous adj. 偶然的
fort〔= fortu〕运气 + itous → 靠运气 → 偶然的
fortune n. 运气；财富
fort 运气 + une → 运气带来财富 → 运气；财富
misfortune n. 不幸
mis 坏 + fortune 运气；财富 → 不幸
unfortunate adj. 不幸的
un 不 + fortunate 幸运的 → 不幸的
数据来源：新东方英语词汇速记大全
相关例句：
In a other word, verb "be" is the most fortuitous verb of change.
换句话说，动词be是个变化最不规则的动词。
It was quite fortuitous the way we met.
我们的相逢实属偶然。
Actually, this is a fortuitous accident, since we can take a look at how to delete a record from the service.
实际上，这是一个幸运的意外，因为我们可以了解如何从该服务删除记录。
In retrospect, though, the timing proved more fortuitous than it initially appeared.
然而，回想起来，事实证明，这个时机要比一开始看上去的更好。
That was a fortuitous question.
那是一个偶然的问题。
He was, by virtue of that fortuitous chance and opportunity which has put so many small men in great positions, the president of the leading bank of the community.
他是社区主导银行的行长，只不是巧合和机遇让这些小人们爬上了这重要的位置而已。