In`fin*i*tes"i*mal (?), a. [Cf. F. infinit'esimal, fr. infinit'esime infinitely small, fr. L. infinitus. See Infinite, a.]
Infinitely or indefinitely small; less than any assignable quantity or value; very small.
Infinitesimal calculus, the different and the integral calculus, when developed according to the method used by Leibnitz, who regarded the increments given to variables as infinitesimal.
© Webster 1913.
In`fin*i*tes"i*mal, n. Math.
An infinitely small quantity; that which is less than any assignable quantity.
© Webster 1913.