conceal vs overlay

conceal

verb
  • To hide something from view or from public knowledge, to try to keep something secret. 

overlay

verb
  • To lay, spread, or apply something over or across; cover. 

  • To put an overlay on. 

  • simple past tense of overlie 

  • To overwhelm; to press excessively upon. 

  • To bet too much money on. 

noun
  • A block of program code that is loaded over something previously loaded, so as to replace the functionality. 

  • A covering over something else. 

  • A decal attached to a computer keyboard to relabel the keys. 

  • A pop-up covering an existing part of the display. 

  • A horse going off at higher odds than it appears to warrant, based on its past performances. 

  • A piece of paper pasted upon the tympan sheet to improve the impression by making it stronger at a particular place. 

  • A cravat. 

  • Odds which are set higher than expected or warranted. Favorable odds. 

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