Webster's Revised Unabridged Dictionary · 1913

Tetratomic

Tetratomic , adjective

[Tetra- + atomic.]

(a)
(Chemistry) Consisting of four atoms; having four atoms in the molecule, as phosphorus and arsenic.
(b)
(Chemistry) Having a valence of four; quadrivalent; tetravalent; sometimes, in a specific sense, having four hydroxyl groups, whether acid or basic.