"染头发"的英语是 "dye hair"。这个短语源自英语单词 "dye"，意思是 "染料" 或 "染色"，和 "hair"，意思是 "头发"。

一些例句如下：

- I want to dye my hair purple.

我想把头发染成紫色。

- She always dyes her hair before going to a party.

她总是在去聚会之前染头发。

- He has dyed his hair black for the past few years.

过去几年他一直把头发染成黑色。

希望这些信息对您有帮助。如果您还有其他问题，请随时联系我。