A compound that is completely dry or "water - free" is called

Anhydrous is the compound that is completely dry or it is water free. example sodium sulfate is referred to as anhydrous sodium sulfate when it is free from water. The anhydrous compound are used as a drying material since without water bonded to its molecules salt will usually absorb moisture it come into contact with and therefore it is used as a dehydrating substance.

Anhydrous is the correct answer