1. Having or capable of exerting power.
2. Effective or potent: a powerful drug.
3. Chiefly Upper Southern US Great: "[Everybody had] a powerful lot to say about faith and good works and free grace ... and I don't know what all" (Mark Twain).
Chiefly Upper Southern US
Very: It was powerful humid.
Our Living Language In the Upper Southern United States the words powerful and mighty are intensives used frequently in the same way as very: Your boy's grown powerful big. The new baby is mighty purty. Powerful is used as an adjective in some expressions: The storm did a powerful lot of harm. In the same dialect region the noun power has, in addition to its standard meaning, the sense of "a large number or amount." This sense appears in the Oxford English Dictionary as common in dialectal British English of the 1700s and 1800s: "It has done a power of work" (Charles Dickens). All these derivative senses of power and might take advantage of the notion of strength inherent in these nouns, making them natural intensives.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus