Adjective
Having three atoms; -- said of certain elements or radicals.
Having a valence of three; trivalent; sometimes, in a specific sense, having three hydroxyl groups, whether acid or basic; thus, glycerin, glyceric acid, and tartronic acid are each triatomic.
Source: Webster's dictionaryIn essence, all UVC is blocked by diatomic oxygen (100–200 nm) or by ozone (triatomic oxygen) (200–280 nm) in the atmosphere. Source: Internet
Ozone cycle overview Three forms (or allotropes ) of oxygen are involved in the ozone-oxygen cycle : oxygen atoms (O or atomic oxygen), oxygen gas ( Omain or diatomic oxygen), and ozone gas ( Omain or triatomic oxygen). Source: Internet