浴室(yù shì) - bathroom, shower room in Mandarin

浴室 (yù shì) is the room with the bath or the shower in it. In a flat or a hotel that room usually holds the lavatory too, so in practice the word often points at the same door as 卫生间 does, but the sense it carries is washing rather than plumbing.

The verbs that go with it are 洗澡 and 冲澡, and the fittings you will meet inside are 浴缸 a bath, 淋浴 a shower, and 毛巾 a towel. Estate agents count them the way English ones do: 两室一厅一浴, two bedrooms, one reception, one bathroom.

The trap is a politeness one and it catches almost every English speaker. In English "bathroom" is mostly a euphemism for the lavatory, and there is no bath in sight when an American asks for one. In Mandarin it is literal. If you need the loo in a restaurant, a shop or someone's flat, ask for the 洗手间 or the 厕所. Asking where the 浴室 is suggests you have turned up for a shower.