FLUX'ION noun [Latin fluxio, from fluo, to flow.]

1. The act of flowing.

2. The matter that flows.

3. Fluxions, in mathematics, the analysis of infinitely small variable quantities, or a method of finding an infinitely small quantity, which being taken an infinite number of times, becomes equal to a quantity given.

In fluxions, magnitudes are supposed to be generated by motion; a line by the motion of a point, a surface by the motion of a line, and a solid by the motion of a surface. And some part of a figure is supposed to be generated by a uniform motion, in consequence of which the other parts may increase uniformly, or with an accelerated or retarded motion, or may decrease in any of these ways, and the computations are made by tracing the comparative velocities with which the parts flow.

A fluxion is an infinitely small quantity, an increment; the infinitely small increase of the fluent or flowing quantity.