milfoil

1. See yarrow.
2. Water milfoil.

[Middle English, from Old French, from Latin mīlifolium : mīlle, thousand + folium, leaf.]

A common wild plant (Achillea millefolium, or yarrow) with finely divided leaves which can be used in salads or chopped to replace chervil or parsley as a garnish.

The noun has one meaning:

Meaning #1: ubiquitous strong-scented mat-forming Eurasian herb of wasteland, hedgerow or pasture having narrow serrate leaves and small usually white florets; widely naturalized in North America
  Synonyms: yarrow, Achillea millefolium