interjection. Used three times in a row, or in combination with other words, to indicate part of a sentence which would be annoying to include, or which is incomprehensible, or which is just unimportant.

noun. One of a set of items which do not need to be specified; often used in conjunction with the catch phrase yadda yadda yadda.

"Yadda, yadda, yadda, here we are today: College football, Dick Clark and Times Square, drunken amateur pyro-wannabes setting off bottle-rockets, Nachos, Champagne etc ..."