backhouse noun2 •(US, Canada) An outhouse: an outbuilding used as a lavatory.[…] the chlorides Mother was always throwing into the little outdoor backhouse […] — 1939 •(dialect) An outbuilding behind the main building, or an annex attached to the rear of it; especially, a scullery or washhouse.[…] to abstene […] fra all melting […] of talloun within thair bak hous […] — 1557 formsbackhouses
