Scientific wild-ass guess (SWAG) is an American English slang term meaning a rough estimate made by an expert in the field, based on experience and intuition. It is similar to the slang word guesstimate, a portmanteau of guess and estimate.
== History ==
The slang term "SWAG" is generally thought to have originated in the US military, either the Army or the Air Force. Journalist Melvin J. Lasky wrote that it was first used casually by US Army General William Westmoreland during the Vietnam War. Westmoreland would sometimes reply "SWAG" to reporters' questions about American failure to neutralize...