infinitesimal: Meaning and Definition of

in•fin•i•tes•i•mal

1. indefinitely or exceedingly small; minute: infinitesimal vessels in the circulatory system.
2. immeasurably small; less than an assignable quantity: to an infinitesimal degree.
3. of, pertaining to, or involving infinitesimals.

1. an infinitesimal quantity.
2. a variable having zero as a limit.