Manganous

Part of speech: adjective

Definitions

1. Containing manganese with a valence of two, as in manganous oxide or manganous chloride
2. Of or relating to manganese compounds where the metal exhibits a +2 oxidation state
3. Designating chemical compounds in which manganese is present with an oxidation state of positive two

Etymology: Manganous is a straightforward chemist's coinage: manganese with the suffix "-ous", which in chemistry marks an element in its lower of two oxidation states. The suffix is the same one found in ferrous and cuprous, so the word simply names manganese in that state. The base word has a longer, more winding history. "Manganese" came into English from French "manganèse", which in turn came from Italian "manganese", a borrowing of Medieval Latin "magnēsia". That Latin term traces back to Greek "Magnēsía", a reference to Magnesia, a region in Thessaly, and the same Greek root gave us the name of the magnet, "Mágnēs". Medieval alchemists and early mineralogists used these related names for several different substances, which is why the element's name took so long to settle.