ague vs ground frost

ague

noun
  • A chill, or state of shaking, as with cold. 

  • The cold fit or rigor of the intermittent fever 

  • An intermittent fever, attended by alternate cold and hot fits. 

verb
  • To strike with an ague, or with a cold fit. 

ground frost

noun
  • The condition of air temperature dropping below the freezing point at or near ground level. 

  • Ice produced by the direct deposition of water vapor on grass, trees and other objects in freezing conditions. 

  • The frozen upper level of soil, caused by the air temperature dropping below the freezing point for a lengthy period of time; in temperate climates the soil thaws completely for the summer and in cold climates it may develop to permafrost. 

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