a colourless tasteless powder consisting chiefly of mercurous chloride, used medicinally, esp as a cathartic. Formula: Hg 2 Cl 2
Word Origin for calomel
C17: perhaps from New Latin calomelas (unattested), literally: beautiful black (perhaps so named because it was originally sublimed from a black mixture of mercury and mercuric chloride), from Greek kalos beautiful + melas black
old name for mercurous chloride, 1670s, from French calomel, supposedly (Littré) from Greek kalos "fair" + melas "black;" but as the powder is yellowish-white this seems difficult. "It is perhaps of significance that the salt is blackened by ammonia and alkalis" [Flood].