(inorganic chemistry) The green, crystalline salt of divalent iron and sulfuric acid, FeSO₄, used as a pigment, and in water treatment.

(chemistry) The chemical compound FeO, iron oxide where iron has a valence of +2.

plural of type II error

(statistics) Accepting the null hypothesis when the null hypothesis is false.

(astronomy) A large nebula of gas and plasma of glowing low density in which star formation has recently taken place.

plural of H II region

The ongoing tensions between the United States of America alongside its European allies and the Russian Federation in the mid-2010s; sometimes called the new "US–Russian Cold War"

(inorganic chemistry) The chemical compound CuO.

Synonym of ferrous chloride

(inorganic chemistry) An inorganic compound with the formula CuCl₂.