floccus vs tussock

floccus

noun
  • A flock or tuft of wool or wool-like hairs; the downy plumage of unfledged birds. 

  • A cloud species which consists of rounded tufts of cloud, often formed by dissipation from larger cloud species. Associated with cirrus, cirrocumulus, altocumulus, and stratocumulus genera. 

tussock

noun
  • A tuft or clump of green grass or similar verdure, forming a small hillock. 

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