It's technically correct but not idiomatic. Technically correct because by the definition that Wikipedia gives (http://en.wikipedia.org/wiki/Public_domain http

It's technically correct but not idiomatic. Technically correct because by the definition that Wikipedia gives (http://en.wikipedia.org/wiki/Public_domain http://en.wikipedia.org/wiki/Public_domain), non-enforcement of a trademark could lead to forfeit of the rights on that trademark, and that is one of the options mentioned in the definition. But not idiomatic because the term is much more commonly used in copyright, rather than trademark, where it has a very specific legal meaning. A copyrighted work enters the public domain when the copyright expires (or in old cases, if the owner failed to renew the copyright).