a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question. Also, interabang.
Popular as it was with writers and admen, the interrobang faced a struggle for mainstream acceptance.
-- Keith Houston, Shady Characters: The Secret Life of Punctuation, Symbols, and Other Typographical Marks, 2013
The Interrobang is not a font -- just a single character. Yet it is so powerful a symbol, and such a flawed and original concept, that it deserves a place alongside the most adventurous typographic innovations of the last century.
-- Simon Garfield, Just My Type, 2011
Interrobang is an Americanism from the mid-1960s. It is a blend of interrogation point, another term for a question mark, and bang, printers' slang for an exclamation point.