Definition of "copperas" []

• See ferrous sulfate. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "At Walton-under-the-Naze they find on the shore copperas-stone in great quantities; and there are several large works called copperas houses, where they make it with great expense."
• "Though often a brilliant colored mineral, it is neither gold nor copper; but it may be associated with one or both of them, as found in North Carolina, and it is valuable of itself, being easily converted into copperas, which is sulphate of iron."
• "Sulphuric acid has also been supposed to be sometimes an ingredient of peat -- which combining with iron, (always present,) would favor sulphate of iron, or copperas, which is a poison to useful plants."