big gun vs howitzer

big gun

noun
  • A large artillery gun or one of the largest-caliber naval guns (as on a battleship). 

  • A person, group, thing, or course of action that is powerful, influential, or particularly effective. 

howitzer

noun
  • A cannon that combines certain characteristics of field guns and mortars, delivering projectiles with medium velocities, usually with relatively high trajectories; normally a cannon with a tube length of 20 to 30 calibers. 

  • A powerfully hit shot. 

verb
  • To attack with a howitzer. 

How often have the words big gun and howitzer occurred in a corpus of books? (source: Google Ngram Viewer )