The Collaborative International Dictionary of English v.0.48:

Oust \Oust\, v. t. [imp. & p. p. Ousted; p. pr. & vb. n.
   Ousting.] [OF. oster, F. [^o]ter, prob. fr. L. obstare to
   oppose, hence, to forbid, take away. See Obstacle, and cf.
   Ouster.]
   1. To take away; to remove.
      [1913 Webster]

            Multiplication of actions upon the case were rare,
            formerly, and thereby wager of law ousted. --Sir M.
                                                  Hale.
      [1913 Webster]

   2. To eject; to expel; to turn out. --Blackstone.
      [1913 Webster]

            From mine own earldom foully ousted me. --Tennyson.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Oust \Oust\, n.
   See Oast.
   [1913 Webster]

WordNet (r) 3.0 (2006):

oust
    v 1: remove from a position or office; "The chairman was ousted
         after he misappropriated funds" [syn: oust, throw out,
         drum out, boot out, kick out, expel]
    2: remove and replace; "The word processor has ousted the
       typewriter"

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "oust":
   bereave, boot out, bounce, break, bust, cashier, cast, cast out,
   chuck out, deconsecrate, defenestrate, defrock, deport, depose,
   dethrone, detrude, disbar, discard, discharge, discrown,
   disenthrone, disinherit, dislodge, dismiss, displace, dispossess,
   divest, drum out, eject, evict, exclude, excommunicate, expel,
   extrude, give the gate, give the hook, heave out, jettison, junk,
   kick downstairs, kick out, kick upstairs, lag, liquidate, lose,
   obtrude, ostracize, overthrow, pension, pension off, purge,
   put out, read out of, reject, relegate, remove, remove from office,
   retire, rob, strip of office, strip of rank, superannuate, suspend,
   throw away, throw out, throw overboard, thrust out, toss out,
   transport, turn out, unchurch, unfrock, unhouse, unkennel,
   unsaddle, unseat, unthrone