triatomic: Meaning and Definition of

tri•a•tom•ic

Pronunciation: (trī"u-tom'ik), [key]
— adj. Chem.
  1. having three atoms in a molecule.
  2. having three replaceable hydrogen atoms.
  3. having three replaceable hydroxyl groups.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.