Infinitesimal /(?)/

In·fin·i·tes·i·mal

Infinitesimal

a.
  1. Infinitely or indefinitely small; less than any assignable quantity or value; very small.

Phrases & Compounds
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.

Infinitesimal

n.
  1. An infinitely small quantity; that which is less than any assignable quantity. (Math.)