corollary vs proofreading

corollary

noun
  • A proposition which follows easily from the proof of another proposition. 

  • A gift beyond what is actually due; an addition or superfluity. 

  • An a fortiori occurrence, as a result of another effort without significant additional effort. 

adj
  • Occurring as a natural consequence or result; attendant; consequential. 

  • Forming a proposition that follows from one already proved. 

proofreading

noun
  • The act or process by which a document is proofread. 

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