A spongy, combustible substance, prepared from fungus (Boletus and Polyporus) which grows on old trees; German tinder; punk. It has been employed as a styptic by surgeons, but its common use is as tinder, for which purpose it is prepared by soaking it in a strong solution of niter.

Amadou is a spongy, flammable substance prepared from bracket fungi. The species generally used is Fomes fomentarius (formerly Ungulina fomentaria or Polyporus fomentarius) which in English is also called horse's hoof fungus or tinder fungus. It is used as tinder (especially after being soaked in a solution of nitre) and in fly fishing, for drying out fly lures.