1. A dominant lesbian; a bull-dyke. Usually has short hair or mullet and dresses in male clothing or dungarees. Her opposite number is the "femme" or "baby doll". (Primarily West Coast usage circa 1950s)
2. Large and/or muscular female of the homosexual persuasion. Many are into rough sex with other dykes, and drive trucks & ride motorcycles. A very "butch" woman.
Reportedly, the actress Tallulah Bankhead had a hankering for diesel-dykes and it opened her up to blackmail by the L.A. mob, which was one reason her movie career never took over.