nucleus
nounUK /ˈnjuː.kli.əs/
US /ˈnuː.kli.əs/
The nucleus is the middle part of a cell that controls what the cell does.
The nucleus is like the brain of the cell.
RELATED WORDS
OTHER MEANINGS
2. The central part of an atom.
Protons and neutrons sit in the nucleus of an atom.
3. The main or most important part of a group or thing.
A small nucleus of volunteers started the club.
4. The central, brighter part of a comet or galaxy.
The comet's nucleus is made of ice and dust.