anvil vs tympanum

anvil

noun
  • The incus bone in the middle ear. 

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

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

  • 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. 

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

tympanum

noun
  • The main portion of the middle ear: the tympanic cavity (cavitas tympani). 

  • A drum-shaped wheel with spirally curved partitions by which water is raised to the axis when the wheel revolves with the lower part of the circumference submerged; used for raising water, as for irrigation. 

  • A membranous resonator in a sound-producing organ in frogs and toads. 

  • A thin tense membrane covering the hearing organ on the leg or body of some insects, sometimes adapted (as in cicadas) for producing sound. 

  • (in certain birds) The labyrinth at the bottom of the windpipe. 

  • The eardrum (tympanic membrane, membrana tympanica). 

  • A vertical recessed triangular space between the sides of a pediment, typically decorated 

  • The recessed triangular space within an arch, and above a lintel or a subordinate arch, spanning the opening below the arch 

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