aigrette vs bittern

aigrette

noun
  • The lesser white heron. 

  • A feather or plume, or feather-shaped item, used as an adornment or ornament. 

  • The feathery crown of some seeds (such as the dandelion). 

bittern

noun
  • Several bird species in the Botaurinae subfamily of the heron family Ardeidae. 

  • The saline substance added to soy milk to coagulate it as a primary step in the production of tofu. 

  • The liquor remaining after halite (common salt) has been harvested from saline water (brine). 

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