knob vs sweet spot

knob

noun
  • The clitoris. 

  • A ball-shaped part of a handle, lever, etc., designed to be grabbed by the hand. 

  • The head of the penis; the glans. 

  • A rounded protuberance, especially one arising from a flat surface; a fleshy lump or caruncle. 

  • A woman's breast. 

  • A contemptible person; dick. 

  • A prominent rounded hill. 

  • A freshman at The Citadel, The Military College of South Carolina. 

  • A rounded control switch that can be turned on its axis, designed to be operated by the fingers. 

  • A prominent, rounded bump along a mountain ridge. 

  • A dollop, an amount just larger than a spoonful (usually referring to butter). 

  • A chunky branch-like piece, especially of a ginger rhizome. 

  • A bulb of the garlic plant consisting of multiple cloves. 

  • A rounded ornament on the hilt of an edged weapon; a pommel. 

verb
  • To have sex with. 

sweet spot

noun
  • The clitoris, prostate gland, or other center of sexual pleasure. 

  • Any place that is optimal for obtaining a certain desirable effect or result. 

  • Any of several places on a bat, racquet, etc., with which to hit a ball, resulting in the latter rebounding with some optimal desirable effect, such as minimum vibration or maximum velocity. 

  • Any set of conditions that is optimal for obtaining a certain desirable effect or result. 

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