Definition of ponceau in US English:

ponceau

(also ponçeau)

noun

  • Any of a series of red azo dyes.

Origin

Late 18th century (in an earlier sense). From French ponceau, transferred uses of ponceau poppy from poun, poon peacock + -cel, diminutive suffix, the flower being so called on account of its vivid colours, which are compared to those of a peacock.