Rock salt Meaning, Definition & Usage

  1. noun naturally occurring crystalline sodium chloride
    halite.

WordNet


Definitions
  1. (Min.), cloride of sodium (common salt) occuring in rocklike masses in mines; mineral salt; salt dug from the earth. In the United States this name is sometimes given to salt in large crystals, formed by evaporation from sea water in large basins or cavities.

Webster 1913