I've never actually seen a definition, so feel free to enlighten me. Since I'm not a regular listener of Rush I didn't know there was an official definition.

What a Dittohead means to me in 500 words or less:

A dittohead is the man who works 3 cubicles away from me who gets his news exclusively from Rush Limbaugh. He is the man who makes it easy for me to keep up on the latest Rush developments, since he parrots all of Rush's words to me practically every time he walks by my cubicle. In fact the dittohead does me a public service, by allowing my listening habits to drift up and down the radio spectrum and even into the FM bracket occassionally without having to worry about what I'm missing on the EIB network. Having one dittohead around is not too bad, however, being a student of moderation, I have observed that living in a state full of dittoheads can be detrimental to the brain. Trust me I live in Idaho.

-Steve G.