Definition of atom in English:

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Pronunciation: /ˈadəm/


1The basic unit of a chemical element.
Example sentences
  • Once removed from an atom, an electron may in turn ionize other atoms or molecules.
  • Dr Lewis said the acrosome reaction involved the channelling of charged calcium atoms, or ions.
  • Lam says that teleporting single atoms and molecules could be perfected within the next ten years.
1.1Atoms as a source of nuclear energy: the power of the atom
More example sentences
  • Heisenberg is already very famous as a scientist, and when the war starts, he will work for the Nazis trying to split the atom and develop an atomic bomb.
  • Rutherford knew that alpha particles, which readily pierced the atom's cloud of electrons, didn't have enough energy to penetrate and pry apart the nucleus.
  • They showed us how to split the atom and harness nuclear fuel so that we might finally meet them as equals.
1.2 [usually with negative] An extremely small amount of a thing or quality: I shall not have one atom of strength left
More example sentences
  • It is the height of hypocrisy for him to complain that Darwinism lacks causal specificity when his own theory lacks any specificity, including one atom of historical concreteness.
  • Was this, as I suspected in every atom of my being, a cooked sausage that just wasn't properly cooked?
  • I will not fail to bring to your notice that this transaction is hitch free and that you should not entertain any atom of fear as all required arrangements have been made for the transfer.

An atom, roughly 108 cm in diameter, consists of a tiny, dense, positively charged nucleus made of neutrons and protons, surrounded by a cloud of negatively charged electrons. Each chemical element consists of atoms that possess a characteristic number of protons. Atoms are held together in molecules by sharing electrons.


Late 15th century: from Old French atome, via Latin from Greek atomos 'indivisible', based on a- 'not' + temnein 'to cut'.

  • Long before scientists were able to prove the existence of atoms, ancient Greek philosophers believed that matter was made up of tiny particles that could not be broken down into anything smaller. The word the Greeks used for this hypothetical particle was atomos ‘indivisible, that cannot be cut up’. By way of Latin atomus, this came into English in the 15th century as atom. The word was used in the early 19th century by the British chemist John Dalton (1766–1844) when he gathered evidence for the existence of these building blocks of matter. A century later the physicist Ernest Rutherford (1871–1937) disproved the theory that the atom could not be divided when he split the atom for the first time in 1919. The term atom bomb was first recorded in The Times on 7 August 1945, the day after the Hiroshima blast. Japan surrendered on 15 August, the date when the Bomb first appeared in a headline in The Times as ‘Victory and the Bomb’. But the English novelist H. G. Wells (1866–1946) was writing about an atomic bomb as early as 1914.

Words that rhyme with atom


For editors and proofreaders

Syllabification: at·om

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