crucial, essential, important, useful, valuable, vital | chief, main, major, primary, prime | dual
The committee has a dual function, both advisory and regulatory.

bodily, brain, liver, mental, etc.
Fortunately, his head injuries left his bodily functions unimpaired.

have | carry out, fulfil, perform, serve
All members carry out their own particular functions. | The club serves a useful function as a meeting place.

charity, official, social
The princess attended a charity function in aid of cancer research.

hold | attend, go to

room
The wedding reception will be held in the Swan Hotel''s function room.

effectively, efficiently, smoothly, successfully, well | perfectly | correctly, normally, properly
All the instruments were functioning normally.

adequately, satisfactorily
Problems arise when the body''s immune system is not functioning adequately.

independently
Can we devise a system in which judges function independently of party poltics?

actually
This model does not describe accurately the way a market economy actually functions.

still
The bombs continued to fall, but somehow the city still functioned.

be able/unable to, can/could
When nutrients are in short supply the body cannot function properly.

begin to | continue to | cease to

fully functioning
The group has now become a fully functioning political organization.