The Collaborative International Dictionary of English v.0.48:

Assignee \As`sign*ee"\, n. [F. assign['e], p. p. of assigner.
   See Assign, v., and cf. Assign an assignee.] (Law)
      (a) A person to whom an assignment is made; a person
          appointed or deputed by another to do some act,
          perform some business, or enjoy some right, privilege,
          or property; as, an assignee of a bankrupt. See
          Assignment
      (c) . An assignee may be by special appointment or deed,
          or be created by jaw; as an executor. --Cowell.
          --Blount.
      (b) pl. In England, the persons appointed, under a
          commission of bankruptcy, to manage the estate of a
          bankrupt for the benefit of his creditors.
          [1913 Webster]

WordNet (r) 3.0 (2006):

assignee
    n 1: (law) the party to whom something is assigned (e.g.,
         someone to whom a right or property is legally transferred)

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "assignee":
   agent, allottee, almsman, almswoman, annuitant, appointee, assign,
   attorney, beneficiary, candidate, deputy, devisee, donee, factor,
   feoffee, grantee, legatary, legatee, licensee, nominee, patentee,
   pensionary, pensioner, proxy, selectee, stipendiary