folio vs verso

folio

noun
  • A page number. The even folios are on the left-hand pages and the odd folios on the right-hand pages. 

  • A page in an account book; sometimes, two opposite pages bearing the same serial number. 

  • A book made of sheets of paper each folded in half (two leaves or four pages to the sheet); hence, a book of the largest kind, exceeding 30 cm in height. 

  • A wrapper for loose papers. 

  • a leaf of a book or manuscript 

  • A page of a book, that is, one side of a leaf of a book. 

  • A sheet of paper folded in half. 

verb
  • to put a serial number on each folio or page of (a book); to page 

verso

noun
  • The left-hand page of a book of a script which reads from left to right, usually having an even page number. 

  • The back side of a flat object which is to be examined visually, as for reading, such as a sheet, leaf, coin or medal; 

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