n. A mineral, arsenic sulfide (AsS), often associated with orpiment and stibnite in lead, silver and gold ores.
the GNU version of the Collaborative International Dictionary of English
n. Arsenic sulphide, a mineral of a brilliant red color; red orpiment. It is also an artificial product.
The Century Dictionary and Cyclopedia
n. Arsenic disulphid (As2S2), a combination of an equal number of sulphur and arsenic atoms; red sulphuret of arsenic, which is found native in transparent crystals, and also massive.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a rare soft orange mineral consisting of arsenic sulphide; an important ore of arsenic
Word Usage
"Several other, less-common minerals contain arsenic, including orpiment, realgar, and enargite, which are arsenic sulfides."