The Collaborative International Dictionary of English v.0.48:

Secern \Se*cern"\, v. t. [imp. & p. p. Secerned; p. pr. & vb.
   n. Secerning.] [L. secernere. See Secrete.]
   1. To separate; to distinguish.
      [1913 Webster]

            Averroes secerns a sense of titillation, and a sense
            of hunger and thirst.                 --Sir W.
                                                  Hamilton.
      [1913 Webster]

   2. (Physiol.) To secrete; as, mucus secerned in the nose.
      --Arbuthnot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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