drop-dead vs impressive

drop-dead

adv
  • Absolutely final; being the deadline, especially in relation to a date set out in a contract upon which adverse consequences will flow if the contract has not been fulfilled. 

  • Very impressively or spectacularly. 

impressive

adj
  • Appealing. 

  • Capable of being impressed. 

  • Making, or tending to make, a positive impression; having power to impress 

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