lumber vs overburden

lumber

verb
  • To load down with things, to fill, to encumber, to impose an unwanted burden on. 

  • To fill or encumber with lumber. 

  • To move clumsily and heavily; to move slowly. 

  • To heap together in disorder. 

noun
  • An erect penis. 

  • Useless or cumbrous material. 

  • A baseball bat. 

  • Wood sawn into planks or otherwise prepared for sale or use, especially as a building material. 

overburden

verb
  • To overload or overtax. 

noun
  • A sterile stratum that lies above the stratum being investigated 

  • The rock and subsoil that lies above a mineral deposit such as a coal seam. 

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