swallowtail vs topcoat

swallowtail

noun
  • A type of tailcoat with two long tapering tails.ᵂᵖ 

  • The forked tail of a swallow. 

  • Anything, such as a burgee, of a similar forked shape. 

  • Any of various butterflies of the family Papilionidae, many of which have a long extension to each hindwing. 

topcoat

noun
  • A light overcoat. 

  • A layer of paint or varnish etc. applied after the undercoat. 

verb
  • To apply a topcoat to. 

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