moss vs slough

moss

verb
  • To become covered with moss. 

  • To cover (something) with moss. 

noun
  • Any of various small, green, seedless plants growing on the ground or on the surfaces of trees, stones, etc.; now specifically, a plant of the phylum Bryophyta (formerly division Musci). 

  • A bog; a fen. 

  • A kind or species of such plants. 

  • Any alga, lichen, bryophyte, or other plant of seemingly simple structure. 

slough

verb
  • To shed (skin). 

  • To slide off (like a layer of skin). 

  • To discard. 

  • To commit truancy, be absent from school without permission. 

noun
  • A small pond, often alkaline, many but not all formed by glacial potholes. 

  • Dead skin on a sore or ulcer. 

  • A muddy or marshy area. 

  • A type of swamp or shallow lake system, typically formed as or by the backwater of a larger waterway, similar to a bayou with trees. 

  • A state of depression. 

  • The skin shed by a snake or other reptile. 

  • A secondary channel of a river delta, usually flushed by the tide. 

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