An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry (non-flushing) toilets may be encountered. The term may also be used to denote the toilet itself, not just the structure.

Outhouses were in use in cities of developed countries (e.g. Australia) well into the second half of the twentieth century. They are still common in rural areas and also in cities of developing countries. Outhouses that are covering pit latrines in densely populated areas can cause groundwater pollution.

Increasingly, "outhouse" is used for a structure outside the main living property that is more permanent in build quality than a shed. In some localities and varieties of English, particularly outside North America, the term "outhouse" refers not to a toilet, but to outbuildings in a general sense: sheds, barns, workshops, etc.