outhouse

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small, enclosed structure having one or two holes in a seat built over a pit and serving as an outdoor toilet.
• noun An outbuilding, as on a farm.

from The Century Dictionary.

• noun A small house or building separate from the main house; an outbuilding; specifically, in law, under the definition of arson, a building contributory to habitation, separate from the main structure, and so by the common-law rules a parcel of the dwelling-house or not, according as it is within or without the curtilage.

from the GNU version of the Collaborative International Dictionary of English.

• noun A small house or building at a little distance from the main house; an outbuilding.
• noun A small building with one or more seats and a pit underneath, intended for use as a toilet; a privy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An outbuilding, a small structure located away, or not directly accessed from, a main building.
• noun North America An outdoor toilet, (or often just a seat over a cesspool) in a wooden cubicle, where the term is usually referring to a permanent facility. Where an outdoor toilet is installed on a temporary basis, the term portable toilet is generally used. The slang terms john and johnny house are sometimes used to identify an outdoor toilet; see also privy.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a small outbuilding with a bench having holes through which a user can defecate