feathering vs rachis

feathering

noun
  • The fitting of feathers to arrows. 

  • Plumage. 

  • Visible offshoots of the trails of ink written on overly absorbent paper. 

  • A feathered texture. 

  • An arrangement of small arcs or foils separated by projecting cusps, frequently forming the feather-like ornament on the inner mouldings of arches. 

rachis

noun
  • The central shaft of a feather. 

  • The main shaft of either a compound leaf, head of grain, or fern frond. 

  • An anatomical shaft or axis in a marine invertebrate. 

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