It depends heavily on the exact usage: http://dictionary.reference.com/browse/quantum?s=t http://dictionary.reference.com/browse/quantum?s=t The salient featur

It depends heavily on the exact usage: http://dictionary.reference.com/browse/quantum?s=t http://dictionary.reference.com/browse/quantum?s=t The salient feature here is that quanta are discrete and a transition from one to another is a jump rather than a smooth or continuous shift.