Green’s Dictionary of Slang

1. (orig. US, also blaah, blah-blah) pompous, banal verbosity; also nonsense.

1918		H.V. O’Brien diary 3 July in Wine, Women and War (1926) 136: [He] pulled old blah about ‘service’, ‘doing one’s bit’, etc.
1920		Eve. Star (Wash., DC) 26 Nov. 16/2: [cartoon caption] Allow me to call to your atten-shun — Miss Blah Blah — the dainty Dashing and darling Queen of the Blah Blah Blah!
1921		H.C. Witwer Leather Pushers 234: A two column blah of romantical hooch about him bein’ a dashin’ cowboy.
1922		Appleton Post-Crescent (WI) 1 May 9/1: Flapper Dictionary blaah – Apple Sauce, anything that is no good.
1927		E. Pound letter 29 Dec. in Paige (1971) 215: Am I expected to respect either myself or anyone else because some graduated ribbon-clerk offers me 75 bucks for writing blah in a false-pearls and undies monthly?
1932		(con. 1917–19) Dos Passos Nineteen Nineteen in USA (1966) 417: What the hell, he’d join the Navy, it was all a lot of blah anyway.
1932		Derby Dly Teleg. 26 Feb. 4/5: I would rather listen to American nasal accents than the cockney ‘whine’ or the ‘blah-blah’ of the Oxford man.
1937		(con. 1905–25) E.H. Sutherland Professional Thief (1956) 18: When the heel is being worked two-handed, the one who is watching will keep up a constant line of talk or blah in order to make the operation seem natural.
1942		W. Winchell On Broadway 3 Feb. [synd. col.] In short, too many people listened to the blah-blah of the isolationists.
1942		K. Williams Diaries 9 Aug. 4: Read She balderdash! tripe! eyewash! blah! etcetera.
1950		New Yorker 4 Feb. 22: The case of the People v. Inescapable Blah [W&F].
1958		M. Allingham Hide My Eyes (1960) 67: ‘Jeremy Blah-blah and Richard Wah-wah,’ he announced.
1977		S. Berkoff East in Decadence and Other Plays (1985) 57: Loose-tongued garbage in the vile [...] with a blah blah.
1995		J. Cameron Vinnie Got Blown Away 72: So much blah, nobody favours getting nicked so there’s mouth like there’s tomorrow.
2000		Hip-Hop Connection Jan./Feb. 35: End of the century, new millennium, blah blah blah...
2010		K. Richards Life 210: We started to get letters from solicitors and everything, Her Majesty’s Government and blah blah blah.
2023		(con. 1962) J. Ellroy Enchanters 131: The Mirror’s standard crime blah-blah.

2. a fool, an idiot.

1923		H.C. Witwer Fighting Blood 325: While I am waiting for this big blah Ryan to give me a tumble.
1927		H.C. Witwer Classics in Sl. 48: This big blah falls for it and both hands drops to the sides of his tights.
1929		H.C. Witwer Yes Man’s Land 309: That large blah has already returned to our midst.
1967–8		Baker et al. CUSS 81: Blah A small or insignificant person.