clearing vs polynya

clearing

noun
  • An open space in the fog etc. 

  • An area of land within a wood or forest devoid of trees. 

  • A sequence of events used to disconnect a call, and return to the ready state. 

  • The act or process of making or becoming clear. 

  • The period in which remaining university places are allocated to remaining students. 

  • A process of exchanging transaction information and authorisation through a central institution or system to complete and settle those transactions. 

  • The act of removing the ball from one's own goal area by kicking it. 

polynya

noun
  • A naturally formed transient area of open water surrounded by sea ice, especially in polar or subpolar seas. 

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