chiefkey
nounUK /ˈtʃiːfkiː/
US /ˈtʃiːfkiː/
A chiefkey is the most important key that opens the main lock.
The guard kept the chiefkey on a chain around his neck.
OTHER MEANINGS
2. The most important piece of information that helps solve a problem.
Good listening was the chiefkey to fixing the team's mistake.
3. A person who holds the main responsibility for something.
She became the chiefkey of the whole project.
4. A small tool used to wind or adjust a machine.
He turned the chiefkey to start the old clock.