B1
to fasten something with a key, or to be fastened with a key
Dictionary examples:
She locked her TV remote to prevent binge-watching during exam week. (0.0)
He locked his phone in the fridge to avoid social media addiction. (0.0)
I locked my textbooks in a safe during summer vacation. (0.0)
Don't forget to lock the door when you go out. (40.7)
If you shut the door, it will lock automatically. (43.2)