land mine vs mining

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. 

mining

noun
  • The activity of placing mines (the explosive devices). 

  • Any activity that extracts or undermines. 

  • The activity of removing solid valuables from the earth. 

  • Creation of new units of cryptocurrency by validating transactions and demonstrating proof of work. 

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