\Mil"foil\, n. [F. mille-feuille, L. millefolium; mille
thousand + folium leaf. See {Foil} a leaf.] (Bot.)
A common composite herb ({Achillea Millefolium}) with white
flowers and finely dissected leaves; yarrow.
{Water milfoil} (Bot.), an aquatic herb with dissected leaves
   ({Myriophyllum}).