noun Physics.
- an atomic species in which the atoms all have the same atomic number and mass number.
- an individual atom in such a species.
noun
- a species of atom characterized by its atomic number and its mass numberSee also isotope
n.1947, from nucleus + -ide. n.
- A type of atom specified by its atomic number, atomic mass, and energy state, such as carbon 14.
- An atomic nucleus identified by its atomic element and its mass number. For example, a carbon-14 nuclide is the nucleus of a carbon atom, which has six protons, with mass number 14 (thus having eight neutrons). See also isotope.