A genus of herbaceous plants (Tribulus) of the order Zygophylleæ, having a hard several- celled fruit, armed with stout spines, and resembling the military instrument of the same name
{i} any of several species of plants with spiny heads or fruit; iron ball with four spikes arranged so that one is always pointing upward (used to hinder passage of cavalries or vehicles)
tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed
caltrops
Etymology
[ 'kal-tr&p, 'kol- ] (noun.) 15th century. Middle English caltrappe, alteration of calketrappe star thistle, from Old English calcatrippe, from Medieval Latin calcatrippa.