Cas`ca·ril'la noun [ Spanish , small thin bark, Peruvian bark, dim. of cáscara bark.] (Botany) A euphorbiaceous West Indian shrub ( Croton Eleutheria ); also, its aromatic bark. Cascarilla bark ( or Cascarilla ) (Medicine) , the bark of Crot... Found on http://www.encyclo.co.uk/webster/C/31