Etymology

American,^[1] origin unclear, perhaps onomatopoeic of blather; perhaps adaptation of dialectal speech, perhaps from yatata or yatter.^[2] Various variant forms appear in the US 1940s–60s; for example, the 1947 American musical Allegro by Oscar Hammerstein II and Richard Rodgers contains a song called “Yatata, Yatata, Yatata,” about cocktail party chatter; see talk page for additional citations.

Popularized in the United States in the late 1990s by TV show Seinfeld, where it appears as a catchphrase, initially in Season 8, Episode 19, entitled “The Yada Yada”, originally aired on April 24, 1997, which centers around the phrase (in the duplicative “yada yada” form).^[3]

Sometimes popularly attributed to Yiddish, but this is dismissed by etymologists. It is perhaps derived from the Norwegian expression "Jada, Jada" which has a similar pronunciation and interpretation.