The Collaborative International Dictionary of English v.0.48:
Polyporus \Po*lyp"o*rus\, n.; pl. Polypori. [NL., fr. Gr.
poly`s many + ? a pore.] (Bot.)
A genus of fungi having the under surface full of minute
pores; also, any fungus of this genus.
Note: Polyporus fomentarius was formerly dried and cut in
slices for tinder, called amadou. Polyporus betulinus
is common in America, and forms very large thick white
semicircular excrescences on birch trees. Several
species of Polyporous are considered edible.