adj. Of, pertaining to, or possessing the ability to speak in two different voices, especially as a ventriloquist.
The Century Dictionary and Cyclopedia
Speaking with two different voices.
Word Usage
"It followed that -- among the futile persons who use serious, long words in talking about mere books, -- aggrieved reproof of my auctorial malversations, upon the one ground or the other, became in 1921 biloquial and pandemic."