Source : Webster's Revised Unabridged Dictionary (1913)

Oppression \Op*pres"sion\, n. [F., fr. L. oppressio.]
   1. The act of oppressing, or state of being oppressed.

   2. That which oppresses; a hardship or injustice; cruelty;
      severity; tyranny. ``The multitude of oppressions.'' --Job
      xxxv. 9.

   3. A sense of heaviness or obstruction in the body or mind;
      depression; dullness; lassitude; as, an oppression of
      spirits; an oppression of the lungs.

            There gentlee Sleep First found me, and with soft
            oppression seized My drowsed sense.   --Milton.

   4. Ravishment; rape. [Obs.] --Chaucer.

Source : WordNet®

oppression
     n 1: the act of subjugating by cruelty; "the tyrant's oppression
          of the people" [syn: {subjugation}]
     2: the state of being kept down by unjust use of force or
        authority: "after years of oppression they finally
        revolted"
     3: a feeling of being oppressed [syn: {oppressiveness}]