n.
Pronunciation: ' kal-tr ə p, ' ko ̇ l-
Variant: also cal · throp \ -thr ə p \
Function: noun
Etymology: Middle English caltrappe, alteration of calketrappe star thistle, from Old English calcatrippe, from Medieval Latin calcatrippa
Date: 15th century
1 a plural but singular or plural in construction : STAR THISTLE 1 b : PUNCTURE VINE also : any of various related herbs (genera Tribulus and Kallstroemia ) of the same family (Zygophyllaceae, the caltrop family)
2 : a device with four metal points so arranged that when any three are on the ground the fourth projects upward as a hazard to the hooves of horses or to pneumatic tires