midrib vs sewer

midrib

noun
  • The strengthened vein down the middle of a flower petal or simple leaf or leaflet. 

  • The continuation of the petiole of a pinnately compound leaf around which the leaflets attach. 

sewer

noun
  • A small tortricid moth, the larva of which sews together the edges of a leaf using silk. 

  • A pipe or system of pipes used to remove human waste and to provide drainage. 

  • One who sews. 

  • A servant attending at a meal who is responsible for seating arrangements, serving dishes, etc. 

verb
  • To provide (a place) with a system of sewers. 

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