The Collaborative International Dictionary of English v.0.48:

Plumbic \Plum"bic\, a. [From Plumbum.] (Chem.)
   Of, pertaining to, resembling, or containing, lead; -- used
   specifically to designate those compounds in which it has a
   higher valence as contrasted with plumbous compounds; as,
   plumbic oxide.
   [1913 Webster]

WordNet (r) 3.0 (2006):

plumbic
    adj 1: relating to or consisting of lead [syn: plumbic,
           plumbous]