Meaning of ATOM in English

/ ˈætəm; NAmE / noun

the smallest part of a chemical element that can take part in a chemical reaction :

the splitting of the atom

Two atoms of hydrogen combine with one atom of oxygen to form a molecule of water.



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

Oxford Advanced Learner's English Dictionary.      Оксфордский английский словарь для изучающик язык на продвинутом уровне.