merbromin Syllabification: (mer·bro·min)Pronunciation: /ˌmərˈbrōmən/Definition of merbromin noun a greenish iridescent crystalline compound that dissolves in water to give a red solution used as an antiseptic. It is a fluorescein derivative containing bromine and mercury. Origin: 1940s: from mercuric + bromo- + -in1merbromin in other Oxford dictionaries Definition of merbromin in the British & World English dictionary