/ ˈmɒlɪkjuːl; NAmE ˈmɑːl-/ noun
( chemistry ) the smallest unit, consisting of a group of atoms, into which a substance can be divided without a change in its chemical nature :
A molecule of water consists of two atoms of hydrogen and one atom of oxygen.
► mo·lecu·lar / məˈlekjələ(r); NAmE / adjective [ only before noun ]:
molecular structure / biology
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WORD ORIGIN
late 18th cent.: from French molécule , from modern Latin molecula , diminutive of Latin moles mass.