infinitesimal

adj. minute, very tiny; pertaining to infinitesimals (Mathematics)

n. variable with a limit of zero (Mathematics); minute quantity, very small amount

Infinitesimals have been used to express the idea of objects so small that there is no way to see them or to measure them. For everyday life, an infinitesimal object is an object which is smaller than any possible measure, whether we measure size, time, chemical concentration, etc. When used as an adjective in the vernacular, "infinitesimal" means extremely small.
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Adjective
1. infinitely or immeasurably small; "two minute whiplike threads of protoplasm"; "reduced to a microscopic scale"
(synonym) minute, microscopic
(similar) small, little

adv. infinitesimally, in an infinitesimal manner, minutely

adj. infinitesimal, minute, very tiny; (Mathematics) pertaining to infinitesimals

adj. infinitesimal, minute, very tiny; pertaining to infinitesimals (Mathematics)