A cruise around the web nets various definitions for cult film. Few of the definitions agree on all points.
I believe the problem in trying to define the term lies in the fact that there's more than one kind of "cult" movie. Just for fun, I'll add my own definitions to the mix.
First I'll describe the universal characteristics of a cult film, and then I'll categorize the different types.
Universal features of a cult film:
• A "cult" film is one whose admirer is mesmerized into watching any time it runs on TV, even if it is already in that fan's personal video library.
• Enough people like the film to make it economically feasible to market it on DVD.
• A great many other people are indifferent to the film, or actively dislike it.
• It is watched at least once a year by the admirer, perhaps on an anniversary or holiday.
Type A: Cheesy Films
This type of cult film did not succeed at the box office, but, thanks to TCM and the ease of movie rental and purchase, has acquired a following of enthusiastic viewers. Something about it is really cheesy, such as the acting style, the plot, special effects, editing, or other aspects of cinematography. The Godzilla films fall into this category.
Type B: Late Bloomers
This type of cult film did not do well at the box office when it was released initially, but has, by way of word of mouth and television screenings, acquired a wide popularity. The best known cult film of this type is It's A Wonderful Life, which has achieved ritual status with the general population. For many families, watching it is an integral part of Christmas holiday celebrations.
Type C: Perennial Successes
These films were smash hits out of the box. Production quality, theme, setting, story, characters, and actors generated the chemistry that gives a movie mass appeal. In this category belong Gone With the Wind, The Wizard of Oz, and the first Star Wars (1977) movie.
Type D: Subversive Films
This category overlaps with the others. Movie producers in general are reluctant to make films with themes or viewpoints that might prove offensive to the general movie-going public. Occasionally, however, films that go against the American grain are made. I think that the Coen brothers films fall into this category. Certainly No Country for Old Men (2007), for all its awards, is a subversive film by Hollywood standards and those of American cultural myth. It dares to say that the pursuit of material wealth corrupts. It says that Evil is as present and as random as Good. It says that ordinary people invite tragedy by the egotistical decisions that they make. It negates the "cowboy" notion of lonerism and individuality. Nobody can be Shane. One man's choice has the ripple effects of a pebble tossed in water.
Here are some of the films that grab me every time. One scene and I'm hooked until the end.
Gone with the Wind (1939)
The Wizard of Oz (1939)
The Maltese Falcon (1941)
Now Voyager (1942)
I Remember Mama (1948)
The Day the Earth Stood Still (1951)
The Night of the Hunter (1955)
Inherit the Wind (1960)
To Kill A Mockingbird (1962)
The Manchurian Candidate (1962)
A Man for All Seasons (1966)
In the Heat of the Night (1967)
Lion in Winter (1968)
Soylent Green (1973)
Clash of the Titans (1981)
A Christmas Story (1983)
The Client (1994)
Galaxy Quest (1999)
O Brother, Where Art Thou? (2000)
Legally Blonde (2001)