n. see black fly.
black hairy tongue (BHT) a harmless condition characterized by the appearance of elongated filiform *papillae on the upper surface of the tongue. The usual cause is an overgrowth of bacteria that accumulate on the papillae and create pigments giving the tongue a black appearance. Known predisposing factors include smoking, excessive consumption of tea and/or coffee, poor oral hygiene, trigeminal *neuralgia, and *dry mouth.... black fly