the GNU version of the Collaborative International Dictionary of English
n. Mild chloride of mercury, Hg2Cl2, a heavy, white or yellowish white substance, insoluble and tasteless, much used in medicine as a mercurial and purgative; mercurous chloride. It occurs native as the mineral horn quicksilver.
The Century Dictionary and Cyclopedia
n. Hemi-, sub-, or protochlorid of mercury, or mercurous chlorid, Hg2Cl2.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a tasteless colorless powder used medicinally as a cathartic
Word Usage
"In the nineteenth century, a mercury compound called calomel was used to treat everything from tuberculosis and parasites to toothaches and constipation."