atom

noun

at·​om ˈa-təm How to pronounce atom (audio)
1
a
: the smallest particle of an element that can exist either alone or in combination
an atom of hydrogen
b
: the atom considered as a source of vast potential constructive or destructive energy
… a largely forgotten legacy of this country's conquest of the atom.William J. Broad
… when Congress passed the Atomic Energy Act in 1954 and allowed private utilities to "harness the atom."Barry Werth
2
: a tiny particle : bit
There's not an atom of truth in what he said.
3
: one of the minute indivisible particles of which according to ancient materialism (see materialism sense 1a) the universe is composed

Did you know?

Some ancient philosophers believed that matter is infinitely divisible, that any particle, no matter how small, can always be divided into smaller particles. Others believed that there must be a limit and that everything in the universe must be made up of tiny indivisible particles. Such a hypothetical particle was called atomos in Greek, which means “indivisible.” According to modern atomic theory, all matter is made up of tiny particles named atoms from the ancient Greek atomos. However, it has turned out that atoms are not indivisible after all. Indeed, the splitting of atoms can be used to produce vast amounts of energy, as in atom bombs.

Examples of atom in a Sentence

There is not an atom of truth to what he said. give me just one atom of information about the novel's surprise ending
Recent Examples on the Web Greatly simplified, Atom Computing uses lasers like tweezers to trap, control and arrange individual ytterbium atoms into an array. Paul Smith-Goodson, Forbes, 2 Oct. 2024 To catch kaons in the act, the experiment sprays a hose of protons at an unmoving target of beryllium atoms. Clara Moskowitz, Scientific American, 1 Oct. 2024 At very low temperatures, entanglement can spread over long distances, enveloping many atoms and giving rise to strange phenomena such as superconductivity. Ben Brubaker, WIRED, 22 Sep. 2024 At a much earlier time, 380,000 years after the Big Bang, the roiling primordial soup of protons, electrons, and photons cooled enough for the particles to team up and form neutral hydrogen atoms. Bydaniel Clery, science.org, 10 Sep. 2024 See all Example Sentences for atom 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'atom.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Middle English, from Latin atomus, from Greek atomos, from atomos indivisible, from a- + temnein to cut

First Known Use

15th century, in the meaning defined at sense 3

Time Traveler
The first known use of atom was in the 15th century

Dictionary Entries Near atom

Cite this Entry

“Atom.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/atom. Accessed 15 Oct. 2024.

Kids Definition

atom

noun
at·​om ˈat-əm How to pronounce atom (audio)
1
: a tiny particle : bit
2
: the smallest particle of an element that has the properties of the element and can exist either alone or in combination
3
: the atom considered as a source of vast potential energy
Etymology

Middle English atom "particle," from Latin atomus (same meaning), derived from Greek atomos "unable to be divided," from a- "not" and temnein "to cut"

Medical Definition

atom

noun
at·​om ˈat-əm How to pronounce atom (audio)
: the smallest particle of an element that can exist either alone or in combination
atomic adjective
atomically adverb

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