An outhouse is a small structure that covers a toilet and is typically separate from the main building. It is a type of toilet without plumbing and is not connected to plumbing, sewer, or septic system. Instead, it sits over a pit, and bacteria that thrive in oxygen break down the waste, with help from other natural processes. Outhouses vary in design and construction, and they are by definition outside the dwelling. They are commonly humble and utilitarian, made of lumber or plywood, and can easily be moved when the earthen pit fills up. Depending on the size of the pit and the amount of use, this can be fairly frequent, sometimes yearly. One of the purposes of outhouses is to avoid spreading parasites such as intestinal worms, notably hookworms, which might otherwise be spread via open defecation.

In North American English, the term "outhouse" is used for the structure over a toilet, usually a pit latrine ("long drop") . However, in British English, "outhouse" means any outbuilding, such as a shed or barn. Under Texas law, an outhouse may not be built within 75 feet of a drinking water well or a human habitation other than the residence to which the privy belongs, without approval from local health authorities. An outhouse also may not be built over an abandoned well or a stream.