Fibret slørsopp, Cortinarius glaucopus, commonly known as the blue-foot webcap, is a basidiomycete mushroom of the genus Cortinarius native to Europe. Schwachknolliger Klumpfuss (German), Cortinaire à pied glauque (French) and Szálaskalapú pókhálósgomba (Hungarian). The fruit bodies of this fungus have convex caps 4 to 10 cm and ochre or tawny in colour with prominent darker brown fibres. Like other members of the genus, young mushrooms are covered in a web-like veil (cortina) from the cap margin to the stipe. The bulbous stipe is pale lilac-blue initially with lower parts fading to yellow-white. The flesh is yellow-white with a blue hue in the upper stipe. The lilac-blue gills are adnate or free, and become brown as the spores mature. The smell, if present, is slightly mealy. The spore print is red-brown and the spores measure 6.5–8.5 by 4.5–5 µm.
Fruit bodies appear from August onwards in deciduous and coniferous forests, often in profuse numbers. It can be found in fairy rings. C. glaucopus forms ectomycorrhizae that are unusually hydrophobic (water-repellent) compared with other fungi, which has led to interest in decoding its genome. DNA studies indicate it may decompose toxic polycyclic aromatic compounds in the soil with specially adapted oxidizing enzymes.