What is a "Mood Disorder" anyway?

Basically, it's a condition where emotions are unregulated for an extended period of time....which refer to these mood states:

Mania.

Hypo-Mania.

Mixed States.

Rapid Cycling.

Euthymia.

Dysthymia.

Mild Depression.

Depression.

Note: "Bipolar Disorder" & "Manic Depression" are the same thing.