Open English Wordnet
Nouns
(n)caltrop, devil's weed, Tribulus terestristropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed
(n)water chestnut, water chestnut plant, caltropa plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits
(n)star-thistle, caltrop, Centauria calcitrapaMediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America