Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
knapweed is a noun meaning "any of various plants of the genus Centaurea having purple thistlelike flowers". It carries one recorded sense.
any of various plants of the genus Centaurea having purple thistlelike flowers
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for knapweed come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.