life-or-death vs substantial

life-or-death

adj
  • Of critical importance to the success of a particular endeavor. 

  • Having death as a possible or even likely outcome; perilous. 

  • Of critical importance to the survival of a living organism. 

substantial

adj
  • Most important; essential. 

  • Not imaginary; real; actual; true; veritable. 

  • Having a substance; actually existing. 

  • Corporeal; material; firm. 

  • Possessed of goods or an estate; moderately wealthy. 

  • Satisfying; having sufficient substance to be nourishing or filling. 

  • Large in size, quantity, or value; ample; significant. 

  • Having good substance; strong; stout; solid; firm. 

noun
  • Anything having substance; an essential part. 

How often have the words life-or-death and substantial occurred in a corpus of books? (source: Google Ngram Viewer )