Rush recently coined the term "low information voter" as sort of a joke. He uses that term instead of "moron." It's the kinder, gentler, non-threatening Rush--his joke.
"Ignorant" or "moron" are so much more concise.
In the same vein, the term "agnostic" comes from the Greek.
"Agnostic (from Ancient Greek ἀ- (a-), meaning "without", and γνῶσις (gnōsis), meaning "knowledge") was used by Thomas Henry Huxley in a speech at a meeting of the Metaphysical Society in 1869[12] to describe his philosophy which rejects all claims of spiritual or mystical knowledge."
"http://en.wikipedia.org/wiki/Agnosticism"
The same term in Latin is:
"ignoramus (n.)
1570s, from an Anglo-French legal term (early 15c.), from L. ignoramus "we do not know," first person present indicative of ignorare "not to know" (see ignorant).
The legal term was one a grand jury could write on a bill when it considered the prosecution's evidence insufficient. Sense of "ignorant person" came from the title role of George Ruggle's 1615 play satirizing the ignorance of common lawyers."
"http://www.etymonline.com/index.php?term=ignoramus"
"Ignoramus" sounds like a good description to me.