What is the meaning of Cudbear?

A violet-red powder, difficult to moisten with water, prepared from certain lichens, especially Ochrolechia tartarea (syn. Lecanora tartarea), and used for making violet or purple dye.

A rim lichen, crabseye lichen (Ochrolechia tartarea, syn. Lecanora tartarea), from which the powder is obtained.

Source: wiktionary.org