greaser

1. One who greases, such as a worker who greases working parts in a machine.
2. Slang. A tough young man, especially one from a white working-class background who is much involved with motorcycles or cars.
3. Offensive Slang. Used as a disparaging term for a Latin American, especially a Mexican.

The noun has one meaning:

Meaning #1: ethnic slur; offensive terms for a person of Mexican descent
  Synonyms: wetback, taco