Tetratomic \Tet`ra*tom"ic\, a. [Tetra- + atomic.] (Chem.)
(a) Consisting of four atoms; having four atoms in the
molecule, as phosphorus and arsenic.
(b) Having a valence of four; quadrivalent; tetravalent;
sometimes, in a specific sense, having four hydroxyl
groups, whether acid or basic.
[1913 Webster]