thicket vs vegetation

thicket

noun
  • A dense, but generally small, growth of shrubs, bushes or small trees; a copse. 

  • A dense aggregation of other things, concrete or abstract. 

  • The collection of many small linked files created when a document is saved in HTML format by some word processors and web site creation software. 

vegetation

noun
  • There were large amounts of vegetation in the forest. 

  • An abnormal verrucous or fibrinous growth 

  • The act or process of vegetating, or growing as a plant does; vegetable growth. 

  • Plants, taken collectively. 

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