hackle vs rectrix

hackle

noun
  • One of the long, narrow feathers on the neck of birds, most noticeable on the rooster. 

  • By extension (because the hackles of a rooster are lifted when it is angry), the hair on the nape of the neck in dogs and other animals; also used figuratively for humans. 

  • Any flimsy substance unspun, such as raw silk. 

  • A feather plume on some soldier's uniforms, especially the hat or helmet. 

  • A type of jagged crack extending inwards from the broken surface of a fractured material. 

  • A feather used to make a fishing lure or a fishing lure incorporating a feather. 

  • An instrument with steel pins used to comb out flax or hemp. 

  • A plate with rows of pointed needles used to blend or straighten hair. 

verb
  • To separate, as the coarse part of flax or hemp from the fine, by drawing it through the teeth of a hackle or hatchel. 

  • To dress (flax or hemp) with a hackle; to prepare fibres of flax or hemp for spinning. 

rectrix

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

  • A governess; a rectoress. 

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