祖先的英语是 "ancestor"。这个词来源于拉丁语，原意是"先祖"。例如：

My ancestors were from Ireland. 我的祖先是来自爱尔兰的。

She traced her ancestors back to the 17th century. 她追溯到了17世纪的祖先。

The ancient ruins are a testament to the ingenuity of our ancestors. 这些古代遗迹证明了我们的祖先的聪明才智。