Question

What is a mood disorder?

Answer 1

It depends on what kind of mood the person is in, but I will discuss the multiple disorders there are.

Depression - A 'down' mood, can give suicidal thoughts, or lowering the elevation of someone's mood.

Bipolar disorder - This is most likely what you're talking about. This is when a person has mood swings and could be happy 1 minute, but sad the next. This is uncontrollable and could possibly make someone unstable.

Answer 2

affective disorder Also called mood disorder.
any mental disorder, as depressive disorder, bipolar disorder, or cyclothymia, in which a major disturbance of feelings or emotions is predominant.