calamus vs covert

calamus

noun
  • A quill; the hard, horny, hollow, and more or less transparent part of the stem or scape of a feather. 

  • Synonym of fistula (“tube for sucking Eucharist wine”) 

  • A palm in genus Calamus, of rattan palms. 

  • The sweet flag, Acorus calamus. 

  • A fish of genus Calamus in family Sparidae; certain porgies. 

covert

noun
  • A feather that covers the bases of flight feathers. 

  • A covering. 

  • A disguise. 

  • Area of thick undergrowth where animals hide. 

  • A hiding place. 

adj
  • Under coverture. 

  • Secret, surreptitious, concealed. 

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