n. A person who mindlessly repeats what he or she has heard.
the GNU version of the Collaborative International Dictionary of English
n. One who simply repeats what he has heard.
The Century Dictionary and Cyclopedia
n. One who merely repeats what has been learned by rote; one who servilely adopts the language or opinions of others.
Word Usage
"While I often remind everyone because almost no one else does that professional anti-evolutionists are anything but clueless, I had no problem assuming that Coulter was indeed just a clueless parroter."