The Collaborative International Dictionary of English v.0.48:

Severalize \Sev"er*al*ize\, v. t.
   To distinguish. [Obs.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

severalize
    v 1: distinguish or separate [syn: severalize, severalise]
    2: mark as different; "We distinguish several kinds of maple"
       [syn: distinguish, separate, differentiate, secern,
       secernate, severalize, severalise, tell, tell
       apart]