Definition of knotgrass in US English:

knotgrass

noun

  • 1A common Eurasian plant of the dock family, with jointed creeping stems and small pink flowers. It is a serious weed in some areas.

    Genus Polygonum, family Polygonaceae: several species, in particular P. aviculare

    • ‘The main weeds dying back were creeping thistle, couch and mature knotgrass.’
    1. 1.1 Any of a number of other plants, especially grasses, with jointed stems.

Pronunciation

knotgrass

/ˈnätɡras/