Of a fortress, place, or state of confinement: strong, secure, well fortified; difficult to attack or otherwise access. Now only in figurative…

Of a place, means of defence, etc.: affording protection or security; proof against danger. Also with for.

Firm, strong; secure, safe. Obsolete.

Of a place or receptacle: affording protection or safety; secure. Now rare.

Of a place, a means of protection, etc.: affording safety. Also figurative.