overburden vs task

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. 

task

verb
  • To oppress with severe or excessive burdens; to tax 

  • To charge, as with a fault. 

  • To assign a task to, or impose a task on. 

noun
  • Any piece of work done. 

  • A difficult or tedious undertaking. 

  • A process or execution of a program. 

  • An objective. 

  • A piece of work done as part of one’s duties. 

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