Green’s Dictionary of Slang

boasting, braggartry, verbal self-aggrandizement.

1860		J.G. Holland Miss Gilbert’s Career (1870) 121: He’s a man, but he’s nothing but pasteboard. He sort of stands round, and spreads and lets off all the big talk he hears.
1874		Sat. Rev. (London) Feb. 280: [With regard to words like ‘psithurism,’ ‘cheirognomy,’ ‘scintillating eyes,’ ‘the phaesimbrotous sun,’] perhaps they have become so accustomed to big talk that, etc [F&H].
1890		Enterprise (Wellington, OH) 1 Oct. 8/1: Goods, such as will recommend themselves [are] more commendable than [...] big talk in big type about astonishingly low prices.
1895		Opelousas Courier (LA) 10 Aug.2/5: I could hustle around and furnish the necessary big talk.
1917		Clay City Times (KY) 18 Oct. 2/3: Big talk does not make big oil wells or many dollars [...] unless it be big lies.
1934		J.H. O’Hara Appointment in Samarra 161: Aw-haw. Big talk.
1937		S. Anderson Winesburg I i: Oh, George was just getting off some big talk.
1939		T. Wolfe Web and the Rock 458: He laughed like a madman. ‘That’s big talk, woman!’.
1952		(con. 1948) G. Mandel Flee the Angry Strangers 78: You know they carry on with their big talk and laughin.
1952		Lait & Mortimer USA Confidential 61: They sent colonizers down to the deep South, loaded with big talk and money for bus-fares.
1956		E. Pound (trans.) Sophocles’ Women of Trachis 14: That’s what comes of big talk [...] Hell’s full of big talkers.
1959		D. Stuart Yandy 64: He’s a bit stupid, that man. He talked every sort of high words, all big talk.
1964		L. Nkosi Rhythm of Violence I iii: Nothing will ever come of this. It’s just big talk.
1973		A. Salkey ‘Is the lan’ I want’ Jamaica (1983) 99: Plenty big talk, / spliff an’ so, / spondulicks, / Panama Man.
1976		P. Theroux Family Arsenal 70: And all his big talk about Rutter.
2005		(con. c.1945) A. Wheatle Island Songs (2006) 16: Him t’ink him so special wid him big house an’ him big talk.
2015		S. King Finders Keepers (2016) 56: All your big talk [...] You’re nothing but a blowhard.