noun

• (figuratively) The outward appearance of something.
  "It was a little unfortunate that the fib unfibbed gave their consultations something the complexion of that close understanding which exists between penitent and confessor."
• (obsolete, medicine) The combination of humours making up one's physiological "temperament", being either hot or cold, and moist or dry.
  "Ne ever is he wont on ought to feed / But todes and frogs, his pasture poysonous, / Which in his cold complexion doe breed / A filthy blood […]"
• (loanword, especially in scientific works translated from German) An arrangement.
  "1909, Ludwig Boltzmann, translated by Kim Sharp and Franz Matschinsky Second there is the level at which the energy or velocity components of each molecule are specified. He calls this a Komplexion, which we translate literally as complexion."

verb

• (transitive) To give a colour to.
  "From the pale refinement of her genteel heroine to the sallow complexioning of poor white trash, Stowe colors her narrative with the hues of the body."