The Collaborative International Dictionary of English v.0.48:

Reimburse \Re`im*burse"\ (-b?rs"), v. t. [imp. & p. p.
   Reimbursed (-b?rst"); p. pr. & vb. n. Reimbursing.]
   [Pref. re- + imburse: cf. F. rembourser.]
   1. To replace in a treasury or purse, as an equivalent for
      what has been taken, lost, or expended; to refund; to pay
      back; to restore; as, to reimburse the expenses of a war.
      [1913 Webster]

   2. To make restoration or payment of an equivalent to (a
      person); to pay back to; to indemnify; -- often reflexive;
      as, to reimburse one's self by successful speculation.
      --Paley.
      [1913 Webster]

WordNet (r) 3.0 (2006):

reimburse
    v 1: pay back for some expense incurred; "Can the company
         reimburse me for my professional travel?"
    2: reimburse or compensate (someone), as for a loss [syn:
       recoup, reimburse]