nipple vs papilla

nipple

noun
  • A pointing stick. 

  • The projection of a mammary gland from which, on female mammals, milk is secreted. 

  • A mechanical device through which liquids or gases can be passed in a regulated manner. 

  • Any small physical protrusion, such as the lumps on the F and J keys on computer keyboards. 

  • A perforated segment that fits into part of the breech of a muzzle-loading gun, on which the percussion cap is fixed. 

  • Any small physical protrusion on an automotive, a machine part or any other part that fits into a groove on another part. 

  • An internally threaded piece which holds a bicycle spoke in place on the rim. 

  • A short tube threaded at both ends, used as a connector. 

  • An artificial nipple (definition 1) used for bottle-feeding infants. 

verb
  • To fit (a baby's bottle, etc.) with a nipple. 

  • To give one's nipple to (a baby) to allow breastfeeding. 

papilla

noun
  • A small fleshy projection on a plant. 

  • Any of the small protuberances on the upper surface of the tongue often containing taste buds. 

  • A vascular process of connective tissue extending into and nourishing the root of a hair, feather, or developing tooth. 

  • Any of the vascular protuberances of the dermal layer of the skin extending into the epidermal layer and often containing tactile corpuscles. 

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