either of two natural dyes. Old fustic, or yellowwood, is derived from the heartwood of dyer's mulberry, a large, tropical American tree (Chlorophora tinctoria, or Maclura tinctoria) of the mulberry family, Moraceae. The dye produces yellows on wool mordanted (fixed) with chromium salts.

The dye termed young fustic (zante fustic, or Venetian sumac) is derived from the wood of the smoke tree (Cotinus coggygria, or Rhus cotinus), a southern European and Asian shrub of the cashew family, Anacardiaceae. Both old and new fustic have been displaced from commercial importance by synthetic dyes.