overbalance vs overburden

overbalance

verb
  • To be more important than; to outweigh. 

  • To throw (someone or something) off balance; to cause to capsize. 

  • To lose one's balance; to fall over. 

  • To cause an imbalance in (something) by means of excess weight or numbers. 

noun
  • Excess of weight or value; something more than an equivalent. 

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 overbalance and overburden occurred in a corpus of books? (source: Google Ngram Viewer )