boulder vs crystal

boulder

noun
  • A large marble, in children's games. 

  • A particle greater than 256 mm in diameter, following the Wentworth scale 

  • A session of bouldering; involvement in bouldering. 

  • A large mass of stone detached from the surrounding land. 

verb
  • To engage in bouldering. 

crystal

noun
  • A piece of glimmering, shining mineral resembling ice or glass. 

  • A fine type of glassware, or the material used to make it. 

  • Crystal meth: methamphetamine hydrochloride. 

  • A solid composed of an array of atoms or molecules possessing long-range order and arranged in a pattern which is periodic in three dimensions. 

  • The glass over the dial of a watch case. 

adj
  • Very clear. 

  • "Do I make myself clear?" / "Crystal." 

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