"smart, stylish," 1868, of unknown origin, perhaps theatrical slang, first attested in a poem by Bret Harte, who said it was a shortened, altered form of magnificat. Related: Niftily; niftiness.
Smart; stylish; neat, slick: a great many niftier and hotter words/ a nifty way to upstage the president (1868+)
adverb: You did that real nifty
noun[origin unknown; called by Bret Harte, in the 1868 example, ''Short for magnificat'']