mercuric oxide
nounMedical Definition of mercuric oxide
: either of two forms of a slightly water-soluble crystalline poisonous compound HgO:
a
: a yellow finely divided powder obtained usually by precipitation from solutions of mercuric chloride and sodium hydroxide and used in antiseptic ointments
b
: a bright red coarse powder obtained by precipitation from hot solutions or by heating a nitrate of mercury and used similarly to the yellow form