The Collaborative International Dictionary of English v.0.48:

Forcible \For"ci*ble\, a. [Cf. OF. forcible forcible, forceable
   that may be forced.]
   1. Possessing force; characterized by force, efficiency, or
      energy; powerful; efficacious; impressive; influential.
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            How forcible are right words!         --Job. vi. 2?.
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            Sweet smells are most forcible in dry substances,
            when broken.                          --Bacon.
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            But I have reasons strong and forcible. --Shak.
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            That punishment which hath been sometimes forcible
            to bridle sin.                        --Hooker.
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            He is at once elegant and sublime, forcible and
            ornamented.                           --Lowth
                                                  (Transl. )
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   2. Violent; impetuous.
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            Like mingled streams, more forcible when joined.
                                                  --Prior.
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   3. Using force against opposition or resistance; obtained by
      compulsion; effected by force; as, forcible entry or
      abduction.
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            In embraces of King James . . . forcible and unjust.
                                                  --Swift.
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   Forcible entry and detainer (Law), the entering upon and
      taking and withholding of land and tenements by actual
      force and violence, and with a strong hand, to the
      hindrance of the person having the right to enter.

   Syn: Violent; powerful; strong; energetic; mighty; potent;
        weighty; impressive; cogent; influential.
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WordNet (r) 3.0 (2006):

forcible
    adj 1: impelled by physical force especially against resistance;
           "forcible entry"; "a real cop would get physical";
           "strong-arm tactics" [syn: forcible, physical,
           strong-arm]

Moby Thesaurus II by Grady Ward, 1.0:

135 Moby Thesaurus words for "forcible":
   accented, accentuated, acid, active, acute, aggressive, animated,
   armipotent, assertive, authoritative, beefy, biting, bouncing,
   brisk, bulldozer, coercive, cogent, corrosive, cutting, decided,
   doughty, drastic, driving, dynamic, effective, emphasized,
   emphatic, energetic, enterprising, enthusiastic, forceful, forcy,
   full of pep, full-blooded, full-strength, go-go, gutsy, gutty,
   hale, hard, hard as nails, hardy, hearty, hefty, high-potency,
   high-powered, high-pressure, high-tension, husky, imperative,
   impetuous, impressive, in force, in power, in red letters,
   incisive, intense, iron-hard, irresistible, italicized, keen,
   kinetic, lively, living, lusty, mettlesome, mighty,
   mighty in battle, militant, mordant, nervous, nervy, obstinate,
   operative, penetrating, peppy, piercing, poignant, pointed,
   positive, potent, powerful, prepotent, puissant, punchy,
   punctuated, red-blooded, robust, robustious, rugged, ruling,
   self-assertive, sensational, severe, sinewed, sinewy, slashing,
   sledgehammer, smacking, snappy, spanking, spirited, stalwart,
   starred, steamroller, steely, stout, strapping, strenuous,
   stressed, striking, stringent, strong, strong as brandy,
   strong as strong, strong-arm, strong-willed, sturdy, take-charge,
   take-over, telling, trenchant, underlined, underscored, valid,
   vehement, vibrant, vigorous, violent, vital, vivacious, vivid,
   zestful, zesty, zippy