Simple Definition of infinitesimal

from our Learner's Dictionary

infinitesimal

adjective

ɪnˌfɪnəˈtɛsəməl How to pronounce infinitesimal (audio)
: extremely small
an infinitesimal moment in time
an infinitesimal difference

Cite this Entry

“Infinitesimal.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/infinitesimal. Accessed 24 Jun. 2026.

Copy Citation
Last Updated: - Updated example sentences

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of pantheon

See Definitions and Examples »

Popular in Grammar & Usage

See More

7 Pairs of Commonly Confused Words

5 Verbal Slip Ups and Language Mistakes

Is it 'nerve-racking' or 'nerve-wracking'?

The Difference Between 'i.e.' and 'e.g.'

Democracy or Republic: What's the difference?
See More

Popular in Wordplay

See More

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

Even More Bird Names that Sound Like Insults (and Sometimes Are)

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

7 Pairs of Commonly Confused Words

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
boy-thinking-light-bulb
Quiz: Are You An Idiom Expert? Figure out what these figures of speech actually ...
See All