ADJ
- 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
VERB + FUNCTION
- have
- carry out, fulfil, perform, serve
- All members carry out their own particular functions. The club serves a useful function as a meeting place
ADJ
- charity, official, social
- The princess attended a charity function in aid of cancer research
FUNCTION + NOUN
- room
- The wedding reception will be held in the Swan Hotel's function room