pəˈligənəm noun
Etymology: New Latin, from Greek polygonon knotgrass ( Polygonum aviculare ), from poly- + -gonon (from gony knee) — more at knee
1. capitalized : a large widely distributed genus (the type of the family Polygonaceae) of herbs having prominent ocreae, thickened nodes, and flowers that are solitary and axillary or in spiked racemes — see knotgrass , persicaria
2. -s : any plant of the genus Polygonum