THE people who compile dictionaries always have ''news'' (n. pl. Oxford English Dictionaries' in-house word for new words). But neologisms are not always newly minted. Take ''yada yada yada,'' which long before ''Seinfeld'' was used by Lenny Bruce.

Jesse Sheidlower, the senior editor in charge of new words at Random House, became convinced of yada yada yada's staying power not only by its history, but also by the existence of well-established parallel expressions (blah blah blah, for instance). He put it in the 1996 Random House Webster's College Dictionary.
However, Michael Agnes, editor in chief of Webster's New World College Dictionary, excluded yada yada yada from his 1996 edition. And having tracked a decline in its use, he is glad that he did. ''This year we would have had to take it out,'' he said.

New words help give each dictionary its personality.

http://www.nytimes.com/1999/08/22/weekinreview/word-for-word-neology-dictionary-game-yada-yada-yada-satisficing-some-not-others.html



neologism, neology
1. a new word, usage, or phrase.
2. the coining or introduction of new words or new senses for established words. See also theology. — neologian, neologist, n. — neologistic, neologistical, adj.