'Pentavalent' definitions:

Definition of 'pentavalent'

(from WordNet)
adjective
Having a valence of five

Definition of 'Pentavalent'

From: GCIDE
  • Pentavalent \Pen*tav"a*lent\, a. [Penta- + L. valens, p. pr. See Valence.] (Chem.) Having a valence of five; -- said of certain atoms and radicals. [1913 Webster]