# fluxion

## fluxion

[fluhk-shuhn]
noun
1.
an act of flowing; a flow or flux.
2.
Mathematics. the derivative relative to the time.

Origin:
1535–45; < Middle French < Late Latin fluxiōn- (stem of fluxiō) a flowing. See flux, -ion

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World English Dictionary
 fluxion (ˈflʌkʃən) —n 1. obsolete maths the rate of change of a function, especially the instantaneous velocity of a moving body; derivative 2. flux a less common word for flux [C16: from Late Latin fluxiō a flowing] 'fluxional —adj 'fluxionary —adj 'fluxionally —adv

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fluxion

in mathematics, the original term for derivative (q.v.), introduced by Isaac Newton in 1665. Newton referred to a varying (flowing) quantity as a fluent and to its instantaneous rate of change as a fluxion. Newton stated that the fundamental problems of the infinitesimal calculus were: (1) given a fluent (that would now be called a function), to find its fluxion (now called a derivative); and, (2) given a fluxion (a function), to find a corresponding fluent (an indefinite integral). Thus, if y = x3, the fluxion of the quantity y equals 3x2 times the fluxion of x; in modern notation, dy/dt = 3x2(dx/dt). Newton's terminology and notations of fluxions were eventually discarded in favour of the derivatives and differentials that were developed by G.W. Leibniz. See also calculus