heavy hitter

WordReference Random House Unabridged Dictionary of American English © 2025

heav′y hit′ter, 

1. Sport a baseball player who makes many extra-base hits.
2. a very important or influential person:
   the secretary of state and other heavy hitters.
• 1975–80
heav′y-hit′ter, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

heavy hitter noun

1. 
   another term for big hitter2