My definition depends on what the bullet does, not what the critter does. How quickly or slowly it expired is not even a factor. I have had complete and utter bullet failures that both scared and angered me but the critter was deader than fried chicken. I've also had bullets that did better than I hoped or expected but the critter still ran 100yds. The difference is what to expect the next time, or the time after that. In the case of abject failure, there won't be a next time.