Noun caltrop has 3 senses
  1. caltrop, devil's weed, Tribulus terestris - tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed
    --1 is a kind of subshrub, suffrutex
    --1 is a member of Tribulus, genus Tribulus
  2. water chestnut, water chestnut plant, caltrop - a plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits
    --2 is a kind of aquatic plant, water plant, hydrophyte, hydrophytic plant
    --2 is a member of Trapa, genus Trapa
    --2 has particulars:
     water caltrop, Jesuits' nut, Trapa natans; ling, ling ko, Trapa bicornis
  3. star-thistle, caltrop, Centauria calcitrapa - Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America
    --3 is a kind of centaury
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