The center portion of the atom, comprised of neutrons and protons. Not that important for most of what we do except its relationship with the orbiting electrons.
The massive, stable part of the atom which contains both protons and neutrons.
Grob’s Basic Electronics, 11th Edition by Mitchel E. Schultz
The central part of an atom containing protons and neutrons.
Electronic Devices : Conventional Current Version, 9th Edition by Thomas L. Floyd