lock down

verb locks down · locking down · locked down

1. transitive To secure (something). But even as the fireball races both skywards and downwards, the mortally-wounded Major Francis Harvey, Royal Marines, crawls over to a voicepipe despite the loss of both legs and orders the magazines locked down and flooded. It's his last act on this Earth; his body will be found later, next to the
2. transitive To blockade and lock (e.g. a building or campus) so as to prevent ingress or egress; to make the occupants (of an area) stay locked indoors for their safety. Police have the area locked down until the situation is all-clear.
3. transitive To limit the use of (a computer network) to only users with permission.
4. transitive To make (an arrangement) secure, definite, or permanent; to fix.
5. slang, transitive To cause (another person) to enter into an exclusive romantic relationship. It took me some time, but I finally locked her down.
6. intransitive To travel through a flight of locks on a waterway in a downhill direction.

   Opposite: lock up