anvil vs fog

anvil

noun
  • A horizontal-topped mass of cloud, shaped like a blacksmith's anvil, that forms before a thunderstorm. 

  • A stone or other hard surface used by a bird for breaking the shells of snails. 

  • The non-moving surface of a micrometer against which the item to be measured is placed. 

  • A heavy iron block used in the blacksmithing trade as a surface upon which metal can be struck and shaped. 

  • The incus bone in the middle ear. 

verb
  • To fashion on, or as if on, an anvil. 

fog

noun
  • A thick cloud that forms near the ground; the obscurity of such a cloud. (Compare mist, haze.) 

  • A silver deposit or other blur on a negative or developed photographic image. 

  • A new growth of grass appearing on a field that has been mowed or grazed. 

  • Distance fog. 

  • A state of mind characterized by lethargy and confusion. 

  • A mist or film clouding a surface. 

  • Tall and decaying grass left standing after the cutting or grazing season. 

  • Moss. 

verb
  • To become obscured in condensation or water. 

  • To practice in a small or mean way; to pettifog. 

  • To cover with or as if with fog. 

  • To obscure in condensation or water. 

  • To make dim or obscure. 

  • To spoil (film) via exposure to light other than in the normal process of taking a photograph. 

  • To disperse insecticide into (a forest canopy) so as to collect organisms. 

  • To become dim or obscure. 

  • To make confusing or obscure. 

  • To pasture cattle on the fog (of), or aftergrass, of; to eat off the fog from (a field). 

  • To become covered with or as if with fog. 

  • To become covered with the kind of grass called fog. 

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