This is the 717th most frequent Italian word.
chiave
Key.
"Chiave" is used here in its literal meaning as a physical object used to unlock things like doors.
Ho bisogno della chiave per aprire la porta.
I need the key to open the door.
"Chiave" is used metaphorically to express an essential or crucial means to an objective.
La chiave del successo è la determinazione.
The key to success is determination.
"Chiave" is used in a musical context to refer to the tonal area or main scale of a piece.