adj. Incalculably, exceedingly, or immeasurably minute; vanishingly small.
adj. Of or pertaining to values that approach zero as a limit.
adj. Very small.
n. A non-zero quantity whose magnitude is smaller than any positive number (by definition it is not a real number).
the GNU version of the Collaborative International Dictionary of English
adj. Infinitely or indefinitely small; less than any assignable quantity or value; very small.
n. An infinitely small quantity; that which is less than any assignable quantity.
The Century Dictionary and Cyclopedia
Infinitely or indefinitely small; less than any assignable quantity.
n. In mathematics, a fictitious quantity so small that by successive additions to itself no sensible quantity, such as the unit of quantity, could ever be generated.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. (mathematics) a variable that has zero as its limit
adj. infinitely or immeasurably small
Word Usage
"That is the one and only actual meaning of the use of the term infinitesimal by Leibniz."