Like I said, you're free to call it interest, return on investment, profit/loss, or whatever other equivalent term you like. Or you can insist that the term interest only applies to guaranteed return (it doesn't). That wasn't the point of my original post.
if you'd like to earn 12% ROI/interest/whatever, there's lots of ways to do that. It's probably safe to say that almost none of those will feature a guaranteed return, but I can't say so categorically either. A friend of mine has a hedge fund that buys up life insurance policies and then collects the payouts. That seems fairly "guaranteed". But, again, we're talking about taxes here, and why it's unwise to over withhold.