-Someone who speaks at great length without saying anything important.
-A person who talks at great length without making much sense.
-A person who blathers on a lot.
From Scots, alteration of blather skate, from "blather" or "blether" - blather + "skate" - a contemptible person
First Known Use: circa 1650
Used in a sentence:
“You know, that blatherskite has the absolutely most ridiculous hair style I’ve ever seen.”
(courtesy of Grandiloquent Word of the Day, on FB or Tumblr)