'Multiple R-Squared', a strange name?

I came across this name many, at least three times, already. But I do not really know what it is. For example, Question set 13-18 of Schweser practice exam 2 AM. There is a R2, an adjusted R2, and this one? I have never seen it before, but suddenly this crops up every where. Anybody has any clue? BTW, I googled and am still confused.

R^2 for Multiple Regression is Multiple R-Squared :slight_smile: