Outhouse

wiktionary

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From Middle English outhous, equivalent to out- +‎ house. Compare Old Norse úthús(“outhouse”).

etymonline

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outhouse (n.)

early 14c., "shed, outbuilding, small house or building separate from the main house," from out- + house (n.). Sense of "a privy" (principally American English) is attested by 1819.