never vs under no circumstance

never

adv
  • Negative particle (used to negate verbs in the simple past tense; also used absolutely). 

  • At no time; on no occasion; in no circumstance. 

  • Not at any other time; not on any other occasion; not previously. 

intj
  • A statement of defiance 

under no circumstance

prep
  • In no case, whatever happens; never. 

How often have the words never and under no circumstance occurred in a corpus of books? (source: Google Ngram Viewer )