WordWeb Online

1. Forceful and definite in expression or action
   "the document contained a particularly forceful guarantee of religious liberty";
   - emphatic
    
2. 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"

See also: assertive, bruising, drastic, emphatic, exclamatory, firm, forcible, impellent, impetuous, physical, self-asserting, self-assertive, sharp, strong, strong-arm

Antonym: forceless