I think of 'responsive' as meaning it gives as much if not more than you put in. I have 4 acoustic guitars, two of which are very responsive, in that they positively sing with overtones and harmonics and false harmonics. When you move from note to note you'll hear overtones. The other two I have by contrast are solid and dependable, they have a very chunky tone and are fun to play but it must be said, aren't nearly as inspiring.