Here are some possibilities:
1. Silence: This is the most straightforward opposite in terms of conveying information. Silence is the absence of any verbal or non-verbal communication.
2. Isolation: This signifies a complete lack of interaction with others, preventing any possibility of communication.
3. Misunderstanding: While it involves communication, it represents the opposite of effective communication. It's the failure to share information or ideas in a way that is received and understood correctly.
4. Disconnection: This emphasizes the lack of a shared understanding or connection between individuals, hindering effective communication.
5. Secrecy: The intentional withholding of information, preventing communication from happening.
6. Distortion: The alteration of information during communication, resulting in inaccurate or misleading transmission.
The best "opposite" for you will depend on the specific context and the type of communication you are thinking about.