If you mean "the lack of communication" or "an error in communication", then, as other people have said, there is not an English word "incommunication". "incommunicado" means to be "out of communication" and "miscommunication" means "an error in communication". However, if you are reporting something you heard then you might have heard something like "Mr. X is in communication with Mr. Y" which means that Mr. X is communicating with Mr. Y.

No, it doesn't. However, the word "incommunication" is a word, though not part of the normal English vernacular and likely not to be understood by most people. Legally, it refers to a person who can not be located or contacted, and thus have lost the right to their rightful property.

I highly doubt it. What are you looking for, the opposite of "excommunication" or the lack of communication??? (The words "incommunicado" and incommunicable do exist, but don't have any additional forms in English.

I think NO

Google it, if Google says "Yes", then it actually exits!!