aqua re·gi·a 
(rējē-ə, rējə)
(rējē-ə, rējə)n.
A corrosive, fuming, volatile mixture of hydrochloric and nitric acids, used for testing metals and dissolving platinum and gold. Also called nitrohydrochloric acid.
[New Latin aqua rēgia : Latin aqua, water + Latin rēgia, feminine of rēgius, royal (because it dissolves gold, the "royal metal").]