Definition of "fluxion"

fluxion

/ˈflʌkʃən/

noun
countable and uncountable, plural fluxions
1. (obsolete, mathematics) The derivative of a function.
2. (rare or archaic) The action of flowing.
  Quotations
  Perhaps he meant that towns are after all excrescences, grey fluxions, where men, hurrying to find one another, have lost themselves.
  1907, E.M. Forster, The Longest Journey, Part III, XXXIII
3. (rare or archaic) A difference or variation.
verb
third-person singular simple present fluxions, present participle fluxioning, simple past and past participle fluxioned
1. (geology) To be distributed in a flowing pattern.
  Quotations
  ...pilotaxitic texture connotes abundant plagioclase microlites prominently fluxioned in an overall sub-parallel manner and locally around phenocrysts (but strictly in a holocrystalline non-glassy matrix).
  1982, Charles James Hughes, Igneous petrology, page 142