The Collaborative International Dictionary of English v.0.48:

Humble \Hum"ble\, v. t. [imp. & p. p. Humbled; p. pr. & vb. n.
   Humbling.]
   1. To bring low; to reduce the power, independence, or
      exaltation of; to lower; to abase; to humilate.
      [1913 Webster]

            Here, take this purse, thou whom the heaven's
            plagues
            Have humbled to all strokes.          --Shak.
      [1913 Webster]

            The genius which humbled six marshals of France.
                                                  --Macaulay.
      [1913 Webster]

   2. To make humble or lowly in mind; to abase the pride or
      arrogance of; to reduce the self-sufficiently of; to make
      meek and submissive; -- often used rexlexively.
      [1913 Webster]

            Humble yourselves therefore under the mighty hand of
            God, that he may exalt you.           --1 Pet. v. 6.

   Syn: To abase; lower; depress; humiliate; mortify; disgrace;
        degrade.
        [1913 Webster]

WordNet (r) 3.0 (2006):

humbling
    adj 1: causing awareness of your shortcomings; "golf is a
           humbling game" [syn: demeaning, humbling,
           humiliating, mortifying]