knotweed Syllabification: (knot·weed)Pronunciation: /ˈnätˌwēd/Definition of knotweed noun a plant of the dock family that typically has sheaths where the leaves join the stems. It is often an invasive weed. Polygonum and other genera, family Polygonaceae: several species, in particular Japanese knotweed knotgrass. knotweed in other Oxford dictionaries Definition of knotweed in the British & World English dictionary
