nouna colourless tasteless powder consisting chiefly of mercurous chloride, used medicinally, esp as a cathartic. Formula: Hg2Cl2
Word origin
C17: perhaps from New Latin
calomelas (unattested), literally: beautiful black (perhaps so named because it was originallysublimed from a black mixture of mercury and mercuric chloride), from Greek
kalos beautiful +
melas black