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]

WordNet (r) 3.0 (2006):

prepossess
    v 1: possess beforehand
    2: cause to be preoccupied; "The idea of his failure
       prepossesses him"
    3: make a positive impression (on someone) beforehand; "A
       prepossessing appearance"
    4: influence (somebody's) opinion in advance [syn: prejudice,
       prepossess]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "prepossess":
   absorb, adopt, appropriate, arrogate, assume, bend, bias, busy,
   colonize, conquer, distort, engage, engross, enslave, hog, imbue,
   immerse, indent, influence, involve, jaundice, jump a claim,
   make free with, make use of, monopolize, occupy, overrun, preempt,
   preengage, prejudice, prejudice against, prejudice the issue,
   preoccupy, requisition, sit on, soak, squat on, subjugate, sway,
   take all of, take it all, take over, take possession of, take up,
   twist, usurp, warp