muzzle vs overburden

muzzle

noun
  • A piece of the forward end of the plow-beam by which the traces are attached. 

  • The protruding part of an animal's head which includes the nose, mouth and jaws. 

  • The mouth or the end for entrance or discharge of a gun, pistol etc., that the bullet emerges from. 

  • A device used to prevent an animal from biting or eating, which is worn on its snout. 

  • A person's mouth. 

verb
  • To bind or confine an animal's mouth by putting a muzzle, as to prevent it from eating or biting. 

  • To bring the muzzle or mouth near. 

  • To restrain (from speaking, expressing opinion or acting); to gag; to silence; to censor. 

overburden

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

  • A sterile stratum that lies above the stratum being investigated 

verb
  • To overload or overtax. 

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