1. Having three atoms; - said of certain elements or radicals 
2. Having a valence of three; trivalent; sometimes, in a specific sense, having three hydroxyl groups, whether acid or basic

Encyclopedia: Triatomic

• permed
• Permian
• Permian period
• Permic
• permille
• permissibility
• permissible
• permissibly
• permission
• permissive
• permissive waste
• permissively
• permissiveness
• permit
• permitter
• permittivity
• permutability
• permutable
• permutableness
• permutation
• permute
• Pernambuco
• pernambuco wood
• pernicious
• pernicious anaemia