powerful (adj.)

c. 1400, pouerful, "mighty, having great strength or power," from power (n.) + -ful. Sense of "capable of exerting great force or power" is from 1580s.

Meaning "of great quality or number" is from 1811; hence the colloquial sense of "exceedingly, extremely" (adv.) is from 1822. Thornton ("American Glossary") notes powerful, along with monstrous,  as "Much used by common people in the sense of very," and cites curious expressions such as devilish good, monstrous pretty (1799), dreadful polite, cruel pretty, abominable fine (1803), "or when a young lady admires a lap dog for being so vastly small and declares him prodigious handsome" (1799).

This gross perversion is common in several of the Western counties of Pennsylvania, to which region I had supposed it was limited. A gentleman informs me, however that it is not unfrequent in the South, and that he has even heard it yoked with weak, as, A powerful weak man. [Seth T. Hurd, "A Grammatical Corrector; or, Vocabulary of the Common Errors of Speech," 1847]

Related: Powerfully; powerfulness.

Others are reading

Definitions of powerful
powerful (adj.)
strong enough to knock down or overwhelm;
Synonyms: knock-down
powerful (adj.)
having great power or force or potency or effect;
powerful drugs
the most powerful government in western Europe
a powerful argument
a powerful bomb
the horse's powerful kick
his powerful arms
powerful (adj.)
having great influence;
Synonyms: potent
powerful (adj.)
(of a person) possessing physical strength and weight; rugged and powerful;
powerful arms
Synonyms: brawny / hefty / muscular / sinewy
powerful (adj.)
displaying superhuman strength or power;
Synonyms: herculean
powerful (adv.)
(Southern regional intensive) very; to a great degree;
that boy is powerful big now
it is powerful humid
Synonyms: mighty / mightily / right