A contrast set is a bounded collection of items, each of which could fill the same slot in a given schema, syntactic structure, or other linguistic environment. The seven days of the week, the fifty United States, the eight Hawaiian islands, the letters in the alphabet, the categories "male" and "female," the students in a class, or the flavors on offer at an ice cream store are all examples of contrast sets. The Google Sets program attempts to generate a list of the members of a contrast set given a few starter members.