Since Microsoft's Encarta is long-since defunct, are it's dictionary's copyright patents now all null and void?

No. Copyrights and patents last until they expire or the owner stops paying the fees needed to keep them in force. They do not become null or void just because the specific product is no longer sold.

Copyrights are not patents. Encarta is gone, Microsoft isn't.

Even if Microsoft, the copyright owner, were dissolved, the copyright, along with other assets, would have been sold to someone and remain enforceable. Elvis Presley is legally dead, but the copyright to his songs remains valid.

microsoft is not defunct and they hold the rights. just because a book is no longer currently being published does not make the contents free for all. copyright does not require continuous publication, many works only have but a single edition. also it would be dishonest to not give proper credit when using a source.

Typical copyrights live for 95 years, whether they're still in use or not. Whether the copyright holder chooses to enforce their copyrights or not is s different matter. Sometimes you can get away with using old copyrighted material because the owner either doesn't care or doesn't know they own the copyrights. Microsoft knows they own the copyrights and does care if someone infringes upon them.

They copyright is still good.

Microsoft still exists.

No. Microsoft still owns the copyrights. Encarta remains a registered trademark Microsoft owns. It is all their intellectual property. If you think Microsoft won't protect its intellectual property, even seeming disused intellectual property, then you have another think coming. There is hardly a company in the world that is more intractable or more possessive or with a tighter grip on its intellectual property rights than Microsoft.

I would assume that since it is out of publication voluntarily, then its former content now comes under fair use if not unrestricted use, just as if it were public domain...because its creator/compiler no longer claims it.