Definition of French willow in English:

French willow

noun

  • 1Any of several European or Eurasian willows (genus Salix), especially the almond-leaved willow, S. triandra (now rare).

  • 2Any of several willowherbs (genus Epilobium), especially rosebay willowherb, E. angustifolium.

Origin

Early 17th century; earliest use found in Philemon Holland (1552–1637), translator.