hardship vs land mine

hardship

noun
  • Difficulty or trouble; hard times. 

  • A burden, a source of difficulty that could impose a barrier. 

verb
  • To treat (a person) badly; to subject to hardships. 

land mine

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

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

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