caltrop

cal·trop  (kltrp, kôl-)

n.

1. Any of various plants of the genera Tribulus and Kallstroemia, having spiny or tuberculate fruits.

2. A Mediterranean species of star thistle (Centaurea calcitrapa) naturalized in North America.

3. See water chestnut.

4. A metal device with four projecting spikes so arranged that when three of the spikes are on the ground, the fourth points upward, used as a hazard to pneumatic tires or to the hooves of horses.

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[Middle English calketrappe, from Norman French and from Old English calcatrippe, thistle, both from Medieval Latin calcatrippa, thistle : possibly from Latin calcre, to tread on; see calque + trappa, trap (of Germanic origin).]

Thesaurus

Noun	1.	caltrop - tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed devil's weed, Tribulus terestris genus Tribulus, Tribulus - annual or perennial herbs or subshrubs of warm regions subshrub, suffrutex - low-growing woody shrub or perennial with woody base
	2.	caltrop - a plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits water chestnut, water chestnut plant genus Trapa, Trapa - small genus of Eurasian aquatic perennial herbs: water chestnut Jesuits' nut, Trapa natans, water caltrop - a variety of water chestnut ling, ling ko, Trapa bicornis - water chestnut whose spiny fruit has two rather than 4 prongs aquatic plant, hydrophyte, hydrophytic plant, water plant - a plant that grows partly or wholly in water whether rooted in the mud, as a lotus, or floating without anchorage, as the water hyacinth
	3.	caltrop - Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America Centauria calcitrapa, star-thistle centaury - any plant of the genus Centaurea