| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| the offspring of a zebra and a donkey. |
| atomic mass | |
| —n | |
| 1. | the mass of an isotope of an element in atomic mass units |
| 2. | short for relative atomic mass See atomic weight |
atomic mass n.
The mass of an atom, usually expressed in atomic mass units.
| atomic mass
The mass of a given atom or molecule, expressed in atomic mass units. Compare atomic weight. See also mass number. |