discoid vs wall plate

discoid

noun
  • A disk-shaped dental excavator designed to remove the carious dentin of a decayed tooth 

adj
  • Shaped like a disc/disk. 

wall plate

noun
  • A piece of timber laid horizontally in or on a wall as a support for a girder, rafter, or joist. 

  • A plate mounted to a wall as a housing. 

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