Green’s Dictionary of Slang

an outhouse, a privy.

1612		N. Field Woman is a Weathercock IV ii: She showed me to a necessary vault. Within a closet in the chamber too.
1618		N. Field Amends for Ladies I i: I met her in the necessarie house i’ th’ morning.
1678		Proc. Old Bailey 3 July n.p.: He took the Tankard with him to the necessary house, only to secure it, and meant to have presently brought it in, having no thoughts of stealing it.
1693		Proc. Old Bailey 31 May n.p.: That he being coming out of the Necessary House, he saw several of the Soldiers about Nichols with their Swords drawn.
1707		N. Ward ‘The Humours of a Coffee-House’ in Writings (1704) 293: My Stomach is so Sick and Head so Giddy (Yauk) that if you don’t lead me to (Yauk) the Necessary-House, I shall be forc’d to do something that I should not do.
1718		Proc. Old Bailey 30 May 4/1: The Prisoner came to his House and called for a Pint of Drink, and afterwards wanted to go to the Necessary House in the Cellar, which he did, and came up again.
1725		Proc. Old Bailey 8 Dec. 6/2: One Day she invited me to go with her to Stepney to take a Treat of Cakes and Ale, and I went; and while we were drinking together, I had Occasion to go to the Necessary House [...] I was no sooner got thither, but she came in after me — and we were very merry together.
1733		Proc. Old Bailey 21 Feb. 94/2: He called me down again, and said, What have you done with the Bag? I have it, says I, but what wou’d you advise me to do with it? Why, says he, you might have thrown it down the Necessary-House or have burnt it, but give it me and I’ll take care of it.
1743		Proceedings Old Bailey 13 Apr. 150/1: He viewed the Seat of the Necessary-House, and put down a long Fork, or Thing with Prongs, and brought up the Body of an Infant; her Father was with me, when the Child was brought up, out of the Necessary-House.
1752		Proc. Old Bailey 19 Feb. 118/2: He asked me whether the necessary house went into the river, or whether I ever emptied it: he told me he had dropped a tin snuff-box in it.
1765		Proc. Old Bailey 17 Apr. 169/1: I was coming out of the public house, going to the necessary house by the water side; I tumbled over this barrel.
1774		Proc. Old Bailey 18 May 207/1: I went to the necessary house: I heard a noise in it; I fetched a candle, put it through the hole, and saw something.
1780		Proc. Old Bailey 10 May 353/2: He sat up on the night of the 30th of March, to attend the night-men who were emptying the necessaries belonging to the houses in Angel Gardens [...] He heard the deceased and a man together in a necessary-house and [...] from what he heard pass, he was convinced they were criminally concerned together.
1796		Proc. Old Bailey 13 Jan. 164/2: What little house, a necessary house?
1815		Proc. Old Bailey 11 Jan. 98/2: I heard some thing wiping the floor of the necessary house, it seemed to me as if with a cloth.
1938		S. Beckett Murphy (1963) 183: I desire that they [i.e. remains] be burnt and placed in a paper bag and brought [...] without pause into what Lord Chesterfield calls the necessary house.
1997–2002		Hope College ‘Dict. of New Terms’ 🌐 necessary facility [...] necessary room n. Referring to the restroom or bathroom.