powder room

a room containing a toilet and washing facilities for women; lavatory.

such a room provided for the use of female guests, as in a restaurant or nightclub.

Origin of powder room

First recorded in 1905–10

I ordered the boatswain to assist the gunner; and by 10 o'clock the powder-room was clear.

A Continuation of a Voyage to New Holland |William Dampier
In his hand the priest could see a piece of binding cord drawn taut as if fastened to something under the powder-room's floor.

The Law of the North (Originally published as Empery) |Samuel Alexander White
As for us, we steered off, to clear away the lumber from our powder-room, as we had nothing left to charge our guns with.

The Red True Story Book |Various
To reach the powder-room, which is always situated in the after-part of a vessel, was easy.

The Secret of the Island |W.H.G. Kingston (translation from Jules Verne)

But mutiny in a Robespierre Convention, above all,—it is like fire seen sputtering in the ship's powder-room!

The French Revolution |Thomas Carlyle

powder room

euphemistic a lavatory for women in a restaurant, department store, etc