As a phrase, this "Semantic Interoperability" is charmingly incomprehensible and empty.
The best definition of "Semantic" that I have found is "All that there is in language except syntax" (http://bit.ly/c44hvy). This is a negative definition -- and so we are little better off than if we had just talked about language. What we have done is lost the half of the audience who admit that they dont know what it means, and want to live a life without such complex vocabulary. I suggest that wherever "semantics" is said "language" should be used instead.
"Interoperability" really needs to be qualified to be clear what or who are interoperating, and to what end. While you can interoperate without language, you cannot use a language without interoperating (private languages being of doubtful utility).
So - those of us who have been saying that we are interested in "semantic interoperability" would do better to say that we are interested in "language" and be done with it.
Those of us interested in semantic interoperability of healthcare information between IT systems, would be better off saying that we are interested in "machine readable languages for healthcare".
By Charlie McCay