1. A period of depression, melancholy, or despondence. I've had the blue devils a lot recently. I find it hard to get out of bed each day. I had trouble coping with the blue devils after Tom left me.

2. An acute attack of delirium resulting from withdrawal or abstinence from alcohol after excessive, prolonged use, especially in the case of alcoholism; known medically as delirium tremens (the "DTs"). I need a drink really badly, I'm getting the blue devils like crazy. You're going to have to deal with the blue devils if you ever hope to beat your alcoholism.

3. Drug slang for depressants. More specifically, the barbiturate amobarbital, which has sedative-hypnotic qualities. I was so strung out on cocaine, I needed a couple of blue devils to make me feel normal again.