The Collaborative International Dictionary of English v.0.48:

Prepossess \Pre`pos*sess"\, v. t. [imp. & p. p. Prepossessed;
   p. pr. & vb. n. Prepossessing.]
   [1913 Webster]
   1. To preoccupy, as ground or land; to take previous
      possession of. --Dryden.
      [1913 Webster]

   2. To preoccupy, as the mind or heart, so as to preclude
      other things; hence, to bias or prejudice; to give a
      previous inclination to, for or against anything; esp., to
      induce a favorable opinion beforehand, or at the outset.
      [1913 Webster]

            It created him enemies, and prepossessed the lord
            general.                              --Evelyn.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prepossessing \Pre`pos*sess"ing\, a.
   Tending to invite favor; attracting confidence, favor,
   esteem, or love; attractive; as, a prepossessing manner. --
   Pre`pos*sess"ing*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prepossessing
    adj 1: creating a favorable impression; "strong and vigorous and
           of prepossessing appearance"