Green’s Dictionary of Slang

excellent, wonderful, the very best; used. adv. to imply completeness.

1900		Atlantic Monthly 522: Dey do say dat she dat bardacious stingy dat she lock up all de vittles w’en she go out in de mornin.
1908		L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:iv 289: bardacious, bardaciously, same as bodacious, etc.
1911		D.T. Cooney Study in Ebony 26: She went to de show, an’ she wuz standin’ ’roun’ lack she ne’er have saw nuffin’ befo’, an’ an ole ape bite it bardacious off.
1926		Van Vechten Nigger Heaven 208: Bardacious! agreed his companion.
1937		Barnard Bulletin (N.Y.) 5 Nov. 2/4: A DICTIONARY OF SLANG WORDS and phrases is being compiled by the WPA Federal Writers’ Project, and they want help. . . . From Harlem come words like ‘bardacious’ (marvelous).