dewlap vs topknot

dewlap

noun
  • The pendulous skin under the neck of an ox, or a similar feature on any other animal. 

  • The sagging flesh on the throat of an elderly human. 

topknot

noun
  • A crest or knot of feathers upon the head or top, as of a bird. 

  • The New Zealand topknot, Notoclinus fenestratus 

  • A small European flounder (Phrynorhombus regius, syn. Rhombus punctatus). 

  • The brown topknot, Notoclinus compressus 

  • A decorative headdress. 

  • A decorative knot of hair on the crown of the head, sometimes having ribbons or feathers. 

  • Several species in the genus Zeugopterus 

  • The Norwegian topknot, Phrynorhombus norvegicus 

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