aigrette vs rectrix

aigrette

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

  • The lesser white heron. 

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

rectrix

noun
  • A flight feather on the tails of birds, used for directional control. 

  • A governess; a rectoress. 

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