Definition of knapweed in English:

knapweed

noun

mass noun
  • A tough-stemmed Eurasian plant that typically has purple thistle-like flower heads, occurring chiefly in grassland and on roadsides.

    Genus Centaurea, family Compositae: several species, including the widespread common (or lesser) knapweed (C. nigra) (also called hardheads)

    • ‘The oil from the seeds of cotton thistles was extracted for fuel and knapweed, centaurea scabiosa, was believed to promote healing of bruises and wounds.’
    • ‘In Montana, gall flies released to limit knapweed turn out to provide a food bonanza for white-footed mice.’
    • ‘Spotted knapweed is not killed by fire, but sagebrush is.’
    • ‘Invasive weeds such as cheatgrass and knapweeds have settled on some 125 million acres of the American West.’
    • ‘Currently, most producers apply chemicals on rangeland in spring or summer, when knapweed begins to flower, but research is showing that fall application may be preferable.’

Origin

Late Middle English (originally as knopweed): from knop (because of its hard rounded involucre or ‘head’) + weed.

Pronunciation

knapweed

/ˈnapwiːd/