noun
1US Black cohosh, Cimicifuga (or Actaea) racemosa (family Ranunculaceae).
2Any of various plants of the family Fabaceae (Leguminosae); specifically those of the genus Crotalaria or Astragalus, both of which are poisonous to livestock when eaten in quantity.
Origin
Late 18th century; earliest use found in Transactions of the American Philosophical Society. From either rattle or rattle + weed.
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