Polyatomic

[,pɒliә'tɒmik]

(adj.) of or relating to a molecule made up of more than two atoms .

Checker: Polly--From WordNet

(a.) Having more than one atom in the molecule; consisting of several atoms.

(a.) Having a valence greater than one.

Typed by Angelo

adj. (chem.) noting elements or radicals with an equivalency greater than two: with more than one atom in the molecule.

Typed by Chauncey