land mine vs projectile

land mine

noun
  • A mine that is placed on land and designed to explode when stepped upon or touched. 

  • A piece of exercise device consisting of a pivoting tube attached to the ground to which a barbell can be fitted to lift it off the ground. 

  • A critical subject or situation with concealed or unpredictable implications. 

projectile

noun
  • an object intended to be or having been fired from a weapon. 

  • any object propelled through space by the application of a force. 

adj
  • Projecting or impelling forward. 

  • Caused or imparted by impulse or projection; impelled forward. 

How often have the words land mine and projectile occurred in a corpus of books? (source: Google Ngram Viewer )