A grindhouse is an American term for a theater that mainly showed exploitation films. It is named after the defunct burlesque theatres, on 42nd Street, New York, where 'bump n' grind' dancing and striptease used to be on the bill. In the film Lady of Burlesque (1943) one of the characters refers to the burlesque theatre, on 42nd Street, where they are performing stripteases and bump and grind dances, as a "grindhouse".
The introduction of television greatly eroded the audience for local and single-screen movie theatres, many of which were built during the cinema boom of the 1930s. In combination with urban decay after white flight out of older city areas in the mid to late 1960s, changing economics forced these theatres to either close or offer something that television could not. In the 1970s these theatres were put to new use as venues for exploitation films , either adult pornography and sleaze, or slasher horror and dubbed martial arts films from Hong Kong.
Grindhouse films are of characteristically poor quality from both an artistic and a technical standpoint. Grindhouse theatres were typically quite seedy. Patrons were attracted not so much by the film, but by the opportunity to spend long periods of time in a darkened theatre where they could sleep, masturbate, utilise prostitutes, drink alcohol, or consume illegal drugs in a permissive environment. This was further facilitated by double, triple, and "all night" bills on a single admission charge.
Some drive-ins screened grindhouse material, but by definition a grindhouse is an indoor theatre.