Definition of walker's clay in US English:

walker's clay

noun

rare
  • Fuller's earth.

Origin

Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. From the genitive of walker, variant of waulker + clay. In some forms from walker + clay.

Pronunciation

walker's clay

/ˌwɔːkəz ˈkleɪ/