dead calm vs insignificant

dead calm

adj
  • Completely still with no waves and no wind. 

noun
  • The condition of a perfectly flat sea with no waves and no wind. 

insignificant

adj
  • Without meaning; not signifying anything. 

  • Not significant; not important, inconsequential, or having no noticeable effect. 

How often have the words dead calm and insignificant occurred in a corpus of books? (source: Google Ngram Viewer )