1. forceful, strong. Powerful, mighty, potent suggest great force or strength. Powerful suggests capability of exerting great force or overcoming strong resistance: a powerful machine like a bulldozer. Mighty now chiefly rhetorical, implies uncommon or overwhelming strength of power: a mighty army. Potent implies great natural or inherent power: a potent influence. 5. influential, convincing, forcible, cogent, effective.