(inorganic chemistry) A white solid, of empirical formula B₂O₃, that is an inorganic polymer, and is used in making glass and enamel and for synthesizing other boron compounds.

(inorganic chemistry, Britain) Alternative spelling of sulfur trioxide

(inorganic chemistry) A corrosive liquid, SO₃, which forms sulfuric acid on contact with water; made commercially by the oxidation of sulfur dioxide.

(inorganic chemistry) The binary compound of nitrogen and oxygen N₂O₃, a pale blue liquid that reacts with water to form nitrous acid.

(poetry) An eight-line poem whose rhyme scheme is ABaAabAB and whose lines are in iambic tetrameter.

(physics) A singlet state formed from three atoms of different colours

(inorganic chemistry) The binary compound of titanium and oxygen, TiO₃, that is a pale yellow solid, and is used to colour ceramics

(chemistry) An industrially important and highly toxic oxide of arsenic that occurs as the mineral claudetite; formula As₂O₃ (though in liquid, gaseous and some solid forms it has molecules of the form As₄O₆).

(organic chemistry) The triglyceride of oleic acid

(organic chemistry) Any trihydroxy alcohol