sealed

Closed by a seal (something to prevent leakage).

Now we are liberal with our innermost secrets, spraying them into the public ether with a generosity our forebears could not have imagined. Where we once sent love letters in a sealed envelope, or stuck photographs of our children in a family album, now such private material is despatched to servers and clouds operated by people we don't know and will never meet.

Preventing entrance.

Of a road: having an asphalt or macadamised surface.

Not subclassable; from which one cannot inherit.