commutator vs tan

commutator

noun
  • An electrical switch, in a generator or motor, that periodically reverses the direction of an electric current. 

  • A binary map in a given group G, given by [g, h] = ghg⁻¹h⁻¹, where g and h are elements of G, which yields the group's identity if and only if the group operation commutes for g and h. 

  • A binary map in a given ring R, given by [a, b] = ab − ba, where a and b are elements of R, which yields the ring's zero element if and only if the multiplication operation commutes for a and b. 

tan

noun
  • A twig or small switch. 

  • Synonym of picul, particularly in Cantonese contexts. 

  • A yellowish-brown colour. 

  • A darkening of the skin resulting from exposure to sunlight or similar light sources. 

  • An Armenian drink made of yoghurt and water similar to airan and doogh 

  • The bark of an oak or other tree from which tannic acid is obtained. 

verb
  • To change an animal hide into leather by soaking it in tannic acid. To work as a tanner. 

  • To kill by gun, to shoot. 

  • To spank or beat. 

  • To change to a tan colour due to exposure to the sun. 

adj
  • Yellowish-brown. 

  • Having dark skin as a result of exposure to the sun or an artificial process intended to mimic this effect. 

num
  • The second cardinal number two, formerly used in Celtic areas, especially Cumbria and parts of Yorkshire, for counting sheep, and stitches in knitting. 

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