The Collaborative International Dictionary of English v.0.48:

Impede \Im*pede"\, v. t. [imp. & p. p. Impeded; p. pr. & vb.
   n. Impeding.] [L. impedire, lit., to entangle the feet;
   pref. im- in + pes, pedis, foot. See Foot, and cf.
   Impeach.]
   To hinder; to stop in progress; to obstruct; as, to impede
   the advance of troops.
   [1913 Webster]

         Whatever hinders or impedes
         The action of the nobler will.           --Logfellow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impeded
    adj 1: made difficult or slow; "we blamed our impeded progress
           on lack of money"