A completely different situation or set of circumstances. Used to emphasize that the reality of something is more extreme than some other, more acceptable condition or situation. Taking a day or two off to deal with the situation is one thing, but being gone from work for nearly a month is something else entirely. I'm beyond disappointed—I'm completely dumbfounded! I mean, being caught drinking a couple beers or smoking a little pot is pretty on par for a kid your age, but dealing hardcore drugs out of your locker is something else entirely.