The Collaborative International Dictionary of English v.0.48:

Suppress \Sup*press"\, v. t. [imp. & p. p. Suppressed; p. pr.
   & vb. n. Suppressing.] [L. suppressus, p. p. of supprimere
   to suppress; sub under + premere, pressum, to press. See
   Sub-, and Press.]
   1. To overpower and crush; to subdue; to put down; to quell.
      [1913 Webster]

            Every rebellion, when it is suppressed, doth make
            the subject weaker, and the prince stronger. --Sir
                                                  J. Davies.
      [1913 Webster]

   2. To keep in; to restrain from utterance or vent; as, to
      suppress the voice; to suppress a smile. --Sir W. Scott.
      [1913 Webster]

   3. To retain without disclosure; to conceal; not to reveal;
      to prevent publication of; as, to suppress evidence; to
      suppress a pamphlet; to suppress the truth.
      [1913 Webster]

            She suppresses the name, and this keeps him in a
            pleasing suspense.                    --Broome.
      [1913 Webster]

   4. To stop; to restrain; to arrest the discharges of; as, to
      suppress a diarrhea, or a hemorrhage.
      [1913 Webster]

   Syn: To repress; restrain; put down; overthrow; overpower;
        overwhelm; conceal; stifle; stop; smother.
        [1913 Webster]

WordNet (r) 3.0 (2006):

suppress
    v 1: to put down by force or authority; "suppress a nascent
         uprising"; "stamp down on littering"; "conquer one's
         desires" [syn: suppress, stamp down, inhibit,
         subdue, conquer, curb]
    2: come down on or keep down by unjust use of one's authority;
       "The government oppresses political activists" [syn:
       oppress, suppress, crush]
    3: control and refrain from showing; of emotions, desires,
       impulses, or behavior [syn: inhibit, bottle up,
       suppress]
    4: put out of one's consciousness [syn: suppress, repress]
    5: reduce the incidence or severity of or stop; "suppress a
       yawn"; "this drug can suppress the hemorrhage"