noun. Pressure sensitivity on an electronic synthesizer, allowing the musician to change the tone or sound of a note after it is struck.

noun. A touch (feature or characteristic) added finally or as an afterthought.

"Mine had a *very* noisy A#5 key (mechanical click), no aftertouch (as advertised on many-a-sites), and the general feel of the keys is nowhere near those of my standard ReMOTE 49."