Semantic Shift

It is also called semantic change. This article lists some of the different types of semantic change (link). It is a rather common occurrence in languages in general and has been studied by linguists for almost two centuries.

MSM seems to be used by both wings of the blogosphere in discussions of biases in the media. Other terms are liberal media and so-called liberal media used by the right and left respectively. In the days of yore, folks discussed the Fourth Estate (link).

Ceci n'est pas un seing.