Translation of "Underwear" in Chinese

My underwear is dirty.

我的內衣髒了

- I'm not wearing any underwear.
- I am not wearing any underwear.

我沒穿內衣。

- All girls wear pink panties.
- All girls wear pink underwear.

所有的女孩都穿粉紅色的內褲。

My wife's underwear is all old, I want to buy her some new ones online.

我妻子的內褲都舊了，我要給她在網上買點新的。