MANIA is Latin means "madness," and the meaning passed ove into English unchanged. Our word mania can mean a mental illness, or at least an excessive enthusiasm. We might call someone a maniac who was wild, violent, and mentally ill--or maybe just really enthusiatic about something. Too much caffeine might make you a bit manic. But the intense mood swings once known as manic-depressive illness are now usually called bipolar disorder instead.