Define depression?

Irrational panic, self deprecation over real and perceived things from past, present and sometimes future, a feeling of dread and loss, self loathing, even of convincing oneself of worthlessness, the want to distance oneself or push others away, doubting oneself and even so bad as wishing you weren't alive. Those are just some things that one feels while dealing with depression. But here's the worst of it, it's not the same for everyone. Each person deals with their own demons and shadows, it may be some of, all of or even more than those things mentioned.

That is more of description of the symptoms, but it is a mental disorder, usually brought on by some kind of trauma, not always, life altering events and even physical chemical imbalances.