nucleus

US /ˈnuː.kli.əs/
UK /ˈnuː.kli.əs/
"nucleus" picture
1.

the central and most important part of an object, movement, or group, forming the basis for its activity and growth

:
•
The family forms the nucleus of society.
•
The city center is the nucleus of economic activity.
:
corecenterhearthubkernel
2.

the central part of an atom, containing protons and neutrons

:
•
The atomic nucleus contains most of the atom's mass.
•
Nuclear reactions occur within the nucleus.
3.

a dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material

:
•
The cell's nucleus controls its growth and reproduction.
•
DNA is stored within the nucleus of the cell.