Moonbat (1) (n) Irrational and Mentally unstable persons of a decidedly liberal political affiliation;
(2) (n) Someone on the extreme edge of whatever their -ism happens to be.

A mentally unstable Liberal who tires to hijack the true meaning of a word and turn it to their advantage. Just as they have with History.
The true definition of Moonbat is not a compliment to Liberals. It is a term used to describe their mental instability and lack of knowledge.

An unthinking or insane leftist -- in other words, most modern leftists.

Moonbat can also be used as an adjective, e.g. a moonbat professor. According to the Wikipedia entry for moonbat, the word was coined in 2002 by the Editor of Samizdata, Perry de Havilland, and was a variation on the name of radical British activist and columnist George Monbiot.

Originally, the term "moonbat" was intended to be more politically neutral, and described wackos on the left and the right, but it quickly acquired its current usage of being applied almost exclusively to those on the left.

The term also references the moon much in the same way that "lunatic" refers to the insanity-causing powers of the full moon (luna = moon). Bloggers occasionally analyze the behavior patterns of various moonbat "species" as if they were actual animals, and even give them satirical Linnaean taxonomical names, such as "moonbattus berkeleyensis".

The entry in the Samizdata glossary indicates that Perry originally coined the full phrase "barking moonbat"; apparently "moonbat" is just a subsequent shortened version of "barking moonbat," rather than being a pre-existing term that was lengthened to barking moonbat.

An extreme leftist, throwing aside logic for political
convenience. A caller to the Howie Carr radio show summed
it up as "These people wear winter clothes in the summer".
Characterized by men in ponytails, sandals with socks,
and 1.20.09 Bush's Last Day bumperstickers. Often seen
at global warming marches that take place during snowstorms.

A pseudo-intellectual progressive type who would be so retarded and or misinformed or so duped by all the hype as to turn our country over to a JUNIOR senator from Illinois who has spent the better part of his term as Senator pimping himself to the American public when he should be proving himself on a senatorial level, retards would include: Hollywood, minorities, college age, first time voters, the cause oriented, Hamas, The Black Panther Party, Nation of Islam.

A term used to describe the political far left wing bordering communistic thinking or socialistic thinking. A term which describes an unthinking political left wing. A term used to describe dishonest and dumb people leaning to the political left wing.

Any number of irrational and hysterical individuals whose self-indulgent intellectual indolence has led them to a visceral hatred of all things western. Moonbats tend to frequent anti-globalization and numerous other forms of rallies, demonstrations, sit-ins, and the like, tend to look dirty, and can frequently be heard using terms such as, "imperialism". The mark of a true moonbat is the total lack of perspective (i.e. "if a dictator provides free healthcare, I like that dictator" - actual moonbat quote).

Derogatory term for a liberal activist, implying that s/he is a lunatic. The opposite of wingnut.

Someone on the extreme edge of the political left who has long abandoned fact & logic in the pursuit of spewing their scocialist crapaganda. (ie Al Franken, Michael Moore, and Janeane Garafalo, to name but a few.) Ann Coulter is the absolute antithesis of a moonbat.