The atomic nucleus is the central part of an atom that contains protons and neutrons. Synonyms for this term include nucleus, atomic core, central core, and atom center. Other words that can be used to describe the atomic nucleus are central region, inner core, nucleus of an atom, and nuclear center. In physics and chemistry, the term atomic core is often used to refer to the nucleus of an atom. While atom center and central core are more general terms that can be used to describe the central part of anything, not just atoms. These synonyms are useful for describing the characteristics of atoms and their components with different word choices.