dead calm vs unconditional

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. 

unconditional

adj
  • Absolute; without conditions, limitations, reservations or qualifications. 

noun
  • That which is not conditional. 

  • A conditional-like structure expressing that the consequent holds true regardless of the particular value of the antecedent. 

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