'heavy hitter' definitions:

Definition of 'heavy hitter'

From: WordNet
noun
An influential person who works hard to promote the causes they are interested in

Definition of 'heavy hitter'

From: GCIDE
  • Hitter \Hit"ter\, n.
  • 1. One who hits or strikes; as, a hard hitter. [1913 Webster]
  • 2. (Baseball) The batter; as, there are two strikes on the hitter. [PJC]
  • heavy hitter
  • 1. A baseball player who gets many extra-base hits.
  • 2. A person who is very important or is very effective at his profession. [PJC]