# infinitesimal

/ˌɪnfɪnɪˈtɛsɪməɫ/ (US) · /ˈɪnfɪnətˌɛsɪməl/ (UK) · CEFR C1 · Adjective

Source: https://englishreference.com/word/infinitesimal
Updated: 2026-10-17

## Definition

extremely small — so small you can hardly see or measure it.

For teachers: extremely small in size or amount, approaching zero. Often emphasizes a difference too small to measure by ordinary means.

## Examples

- The difference in weight feels infinitesimal to me.
- The doctor says the risk from one scan is infinitesimal compared to the benefit of finding the problem early.
- Even an infinitesimal error in the initial calculations widened over months, until the bridge design required a costly revision.

## Synonyms

minute, Tiny, microscopic, minuscule

## Antonyms

huge, enormous, vast, immense

## Usage notes

- Typically placed before the noun it modifies; also used predicatively after linking verbs such as 'be' or 'seem'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.