Infinitesimal, a.
Etymology: [Cf. F. infinitésimal, fr. infinitésime 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.
1 other Webster entry under this spelling
Infinitesimal, n. (Math.)
An infinitely small quantity; that which is less than any assignable quantity.
Shades of meaning
Fernald lists infinitesimal only as an antonym, under large.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given