riddle vs separate

riddle

verb
  • To fill or spread throughout; to pervade. 

  • To fill with holes like a riddle. 

  • To speak ambiguously or enigmatically. 

  • To put something through a riddle or sieve; to sieve; to sift. 

  • To solve, answer, or explicate a riddle or question. 

noun
  • A board with a row of pins, set zigzag, between which wire is drawn to straighten it. 

  • A verbal puzzle, mystery, or other problem of an intellectual nature. 

  • A sieve with coarse meshes, usually of wire, for separating coarser materials from finer, as chaff from grain, cinders from ashes, or gravel from sand. 

  • An ancient verbal, poetic, or literary form, in which, rather than a rhyme scheme, there are parallel opposing expressions with a hidden meaning. 

  • One of the pair of curtains enclosing an altar on the north and south. 

separate

verb
  • To divide (a thing) into separate parts. 

  • To disunite from a group or mass; to disconnect. 

  • To cause (things or people) to be separate. 

  • To divide itself into separate pieces or substances. 

adj
  • Apart from (the rest); not connected to or attached to (anything else). 

  • Not together (with); not united (to). 

noun
  • A printing of an article from a periodical as its own distinct publication and distributed independently, often with different page numbers. 

  • Anything that is sold by itself, especially articles of clothing such as blouses, skirts, jackets, and pants. 

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