Fluxion /(?)/

Flux·ion

Fluxion

n.
  1. The act of flowing.
  2. The matter that flows.
  3. Fusion; the running of metals into a fluid state.
  4. An unnatural or excessive flow of blood or fluid toward any organ; a determination. (Med.)
  5. A constantly varying indication.
    Less to be counted than the fluxions of sun dials.
  6. The infinitely small increase or decrease of a variable or flowing quantity in a certain infinitely small and constant period of time; the rate of variation of a fluent; an incerement; a differential. (Math.)