infinitesimal

[in-fin-i-tes-uh-muhl]

adjective

1. exceedingly small; minute.

   Capillaries, the infinitesimal vessels in our circulatory system, are small enough that red blood cells must flow through them single-file.

2. Mathematics.

   1. immeasurably small; less than an assignable quantity.

      An infinitesimal number is never zero, but it comes pretty close.

   2. of, relating to, or involving variables having zero as a limit.

      infinitesimal calculus.

noun

1. an infinitesimal quantity.

2. Mathematics.,  a variable having zero as a limit.

infinitesimal

/ ˌɪnfɪnɪˈtɛsɪməl /

adjective

1. infinitely or immeasurably small

2. maths of, relating to, or involving a small change in the value of a variable that approaches zero as a limit

noun

1. maths an infinitesimal quantity

infinitesimal

1. Capable of having values approaching zero as a limit.

1. A function or variable continuously approaching zero as a limit.

Other Word Forms

• infinitesimality noun
• infinitesimalness noun
• infinitesimally adverb

Word History and Origins

Origin of infinitesimal¹

First recorded in 1645–55; from New Latin infīnītēsim(us), equivalent to Latin infīnīt(us) infinite + -ēsimus suffix of ordinal numerals + -al ¹

Example Sentences

“A tiny amount of toxic material, even if it’s infinitesimally small, can still have really major health effects,” Lo said.

From Los Angeles Times

Facebook ads from Russian bot farms that made up an infinitesimal fraction of the content voters were consuming in 2016 were blown up into a huge scandal.

From Salon

According to the Heritage Foundation, a conservative organization, only 12 voter fraud cases have been prosecuted in California since 2021 — an infinitesimal fraction of millions of ballots cast.

From Los Angeles Times

Art often is just a business, but a dangerous one: Changing people by an infinitesimal degree, Castleberry knows, has a way of thoroughly warping and wrecking human lives.

From Los Angeles Times

But he also said the numbers suggested that noncitizen voting “is an infinitesimal, small issue.”

From Salon

Related Words

• imperceptible 
• insignificant 
• microscopic 
• minuscule 
• negligible