Systems

The elevators in a skyscraper are vital systems.

School systems have to cope with changing numbers of pupils.

Our policies and systems are getting outdated and need revising, but to try to swap horses while crossing a stream might be dangerous.

All systems are go.

The political systems of Britain and Japan have a great deal in common.

Because of modern communication and transportation systems, the world is getting smaller.

People needed a more practical system of exchange, so various money systems developed.

With Windows OS systems 'administrator account' corresponds to 'root'.

For code-type locks that don't need a key, there are 'free dial' systems where you can set any number you like, and fixed types where the number is set in advance.

In short some guns have excellent security systems to prevent accidental firing (e.g. when dropped), others don't.