The Collaborative International Dictionary of English v.0.48:

Slavonian \Sla*vo"ni*an\, Slavonic \Sla*von"ic\, a.
   1. Of or pertaining to Slavonia, or its inhabitants.
      [1913 Webster]

   2. Of or pertaining to the Slavs, or their language.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slavonian \Sla*vo"ni*an\, n.
   A native or inhabitant of Slavonia; ethnologically, a Slav.
   [1913 Webster] Slavophil