pow·er·ful / ˈpou(-ə)rfəl/ • adj. having great power or strength: a fast, powerful car computers are now more compact and powerful. ∎ (of a person, organization, or country) having control and influence over people and events: the world's most powerful nation. ∎ having a strong effect on people's feelings or thoughts: his photomontages are powerful antiwar images.• adv. chiefly dial. very: walking in this weather is powerful hot work.DERIVATIVES: pow·er·ful·ly / -f(ə)lē/ adv.pow·er·ful·ness n.