When debriefing SEAD missions, pilots and planners usually classify the mission outcome as either a "soft kill" or a "hard kill".
The term "hard kill" speaks more or less for itself. It implies the destruction of one or more of the enemy air defenses and the successful completion of the friendly mission.
"Soft kill" also denotes a successful friendly mission, but no destruction of enemy air defenses. The idea behind this being a kill, is simply that in order to avoid destruction of their air defenses, the enemy shut it down or kept it non-operating for the duration of the attack.
During Operation Allied Force, most kills by allied SEAD aircraft were soft.