Source : Webster's Revised Unabridged Dictionary (1913)

Forceful \Force"ful\, a.
   Full of or processing force; exerting force; mighty. --
   {Force"ful*ly}, adv.

         Against the steed he threw His forceful spear.
                                                  --Dryden.

Source : WordNet®

forceful
     adj 1: characterized by or full of force or strength (often but not
            necessarily physical); "a forceful speaker"; "a
            forceful personality"; "forceful measures"; "a
            forceful plan for peace" [ant: {forceless}]
     2: forceful and definite in expression or action; "the document
        contained a particularly emphatic guarantee of religious
        liberty" [syn: {emphatic}]