atom

noun

• 1the smallest particle of a chemical element that can exist.
• (usually the atom) atomic particles as a source of nuclear energy:the power of the atom
• [usually with negative] an extremely small amount of something:I shall not have one atom of strength left

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

• 2 [usually as modifier] Canadian a level of amateur sport, typically involving children aged between nine and eleven:eight atom hockey teams