atom

[at-uhm]

noun

1. Physics.

   1. the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element.

   2. an atom with one of the electrons replaced by some other particle.

      muonic atom;

      kaonic atom.

2. Energy.,  this component as the source of nuclear energy.

3. a hypothetical particle of matter so minute as to admit of no division.

4. anything extremely small; a minute quantity.

   Synonyms: whit, jot, iota, scintilla, speck, shred

atom

/ ˈætəm /

noun

1. 1. the smallest quantity of an element that can take part in a chemical reaction

   2. this entity as a source of nuclear energy See also atomic structure

      the power of the atom

2. any entity regarded as the indivisible building block of a theory

3. the hypothetical indivisible particle of matter postulated by certain ancient philosophers as the fundamental constituent of matter See also atomism

4. a very small amount or quantity; minute fragment

   to smash something to atoms

   there is not an atom of truth in his allegations

atom

1. The smallest unit of an element, consisting of at least one proton and (for all elements except hydrogen) one or more neutrons in a dense central nucleus, surrounded by one or more shells of electrons. In electrically neutral atoms, the number of protons equals the number of electrons. Atoms remain intact in chemical reactions except for the removal, transfer, or exchange of certain electrons.

2. Compare compound See also ion isotope orbital

atom

1. A unit of matter; the smallest unit of a chemical element. Each atom consists of a nucleus, which has a positive charge, and a set of electrons that move around the nucleus. (See Bohr atom.)

Atoms link together to form molecules.

Word History and Origins

Origin of atom¹

First recorded in 1350–1400; Middle English attomos, athomus, from Latin atomus, from Greek átomos, noun use of átomos “undivided,” equivalent to a- a- ⁶ + tomós “divided,” from témnein “to cut”

Word History and Origins

Origin of atom¹

C16: via Old French and Latin, from Greek atomos (n), from atomos (adj) that cannot be divided, from _a- ¹ + temnein to cut

Example Sentences

While the Chinese see Japanese aggression as a defining, and devastating, moment in their past, Japanese history focuses on its own victimhood - the destruction caused by the atom bombs and post-war recovery.

From BBC

The AI then learns how bacteria are affected by different molecular structures, built of atoms such as carbon, oxygen, hydrogen and nitrogen.

From BBC

The mayor of Nagasaki has appealed for an end to the wars raging in the world on the 80th anniversary of the US atom bomb attack which destroyed the Japanese city.

From BBC

Those who survived the atom bomb, along with their descendants, continue to live in the long shadow of that day – wrestling with disfigurement, pain, and a decades-long fight for justice that remains unresolved.

From BBC

It’s like an atom bomb going off in your backyard — it’s so horrible that you just sort of cling to your positive human emotion.

From Los Angeles Times