cu·pram·mo·ni·um \|k(y)üprə|mōnēəm, -nyəm\noun (-s) Etymology:cupr- + ammonium 1.: any of certain complex ammino radicals or cations containing copper and ammonia; especially: the bivalent tetrammine-copper cation Cu(NH3)4 compounds of which are formed by the action of ammonia on ordinary cupric compounds 2.: cuprammonium solution 3.: cuprammonium rayon