ephemeral vs unstoppable

ephemeral

adj
  • Usually dry, but filling with water for brief periods during and after precipitation. 

  • Lasting for a short period of time. 

  • Existing for only one day, as with some flowers, insects, and diseases. 

noun
  • Something which lasts for a short period of time. 

unstoppable

adj
  • Unable to be stopped. 

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