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What is the origin of infinitesimal?
Infinite, as you probably know, means "endless" or "extending indefinitely." It is ultimately from Latin infīnītus, the opposite of fīnītus, meaning "finite." The notion of smallness in infinitesimal derives from the mathematical concept that a quantity can be divided endlessly; no matter how small, it can be subdivided into yet smaller fractions, or infinitesimals. The concept was still in its infancy in the early 1700s when Irish philosopher George Berkeley observed that some people "assert there are infinitesimals of infinitesimals of infinitesimals, etc., without ever coming to an end." He used the word in a mathematical sense, too, referring to "infinitesimal parts of finite lines." Later, the adjectival form acquired a general sense applicable to anything too small to be measured.
Synonyms of infinitesimal
Examples of infinitesimal in a Sentence
ABC News, 23 Mar. 2026
The chances of that are infinitesimal, he’s told.
—Natalie Oganesyan, Deadline, 23 Mar. 2026
Leila Sloman, Quanta Magazine, 25 Mar. 2026
But neither a chart of geology’s eons, eras, and periods, nor a calculus of infinitesimals, can eliminate a sense of awe in the face of geological time.
—Lewis Hyde, Harpers Magazine, 18 June 2025
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Cite this Entry
“Infinitesimal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infinitesimal. Accessed 31 Mar. 2026.
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