noun · a spiked metal obstacle or ancient weapon (often called an iron caltrop) used to impede movement

城墙外撒满了铁蒺藜，以防敌军骑兵突袭。

noun · the puncture vine or caltrop plant (Tribulus terrestris), known for its spiny fruit

这种草地里长满了蒺藜，走路要小心刺脚。