From Echoes of Angmar

Debuffs are negative status effects such as stat decreases. The term "debuff" is usually used to refer to effects which weaken the target without hampering their freedom, while "Crowd Control" (CC) is used to refer to status effects that remove the target's ability to move or use abilities, e.g., stuns, dazes, disarms, etc.

Some examples of debuffs: Trick: Disable, Fire-lore, Telling Mark