General:
* Convey
* Express
* Share
* Transmit
* Impart
* Exchange
* Discuss
* Dialogue
* Interact
* Converse
Formal:
* Disseminate
* Articulate
* Elucidate
* Inform
* Explain
Informal:
* Get across
* Let someone know
* Tell
* Talk to
* Chat with
Specific:
* Write: Compose, draft, pen
* Speak: Say, utter, pronounce
* Sign: Gesture, signal, motion
The best synonym will depend on the specific situation and the intended meaning.