ending vs perpetual

ending

noun
  • A termination or conclusion. 

  • The last part of something. 

  • The last morpheme of a word, added to some base to make an inflected form (such as -s in "dogs"). 

perpetual

adj
  • Set up to be in effect or have tenure for an unlimited duration. 

  • Continuing; uninterrupted. 

  • Lasting forever, or for an indefinitely long time. 

  • Flowering throughout the growing season. 

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