berg vs ice cap

berg

noun
  • An iceberg. 

  • mountain 

ice cap

noun
  • An ice pack designed to be worn on the head. 

  • A permanent expanse of ice encompassing a large geographical area, e.g. in Earth's polar zones or at high elevation. 

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