| 1. | Chemistry, Physics. the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound. |
| 2. | Chemistry. a quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule. |
| 3. | any very small particle. |
A combination of two or more atoms held together by a force between them. (See covalent bond and ionic bond.)
molecule mol·e·cule (mŏl'ĭ-ky&oomacr;l')
n.
The smallest particle into which an element or a compound can be divided without changing its chemical and physical properties; a group of atoms that is held together chemically.