glade vs hummock

glade

noun
  • A bright surface of ice or snow. 

  • An everglade. 

  • An open passage through a wood; a grassy open or cleared space in a forest. 

  • An open space in the ice on a river or lake. 

hummock

noun
  • A ridge or hill of ice in an ice field. 

  • A fistful. 

  • A small hill; a hillock; a knoll. 

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