• WordNet 3.6
    • n caltrop Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America
    • n caltrop a plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits
    • n caltrop tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed
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Webster's Revised Unabridged Dictionary
    • Caltrop (Bot) 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. The species grow in warm countries, and are often very annoying to cattle.
    • Caltrop (Mil) An instrument with four iron points, so disposed that, any three of them being on the ground, the other projects upward. They are scattered on the ground where an enemy's cavalry are to pass, to impede their progress by endangering the horses' feet.
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Century Dictionary and Cyclopedia
    • n caltrop Formerly, a military instrument with four iron points disposed in such a manner that, three of them being on the ground, the fourth pointed upward. Caltrops were scattered on the ground where an enemy's cavalry were to pass, to impede their progress by wounding the horses' feet.
    • n caltrop plural Broken pottery or coarse pots of easily broken earthenware, or other things adapted to wound horses' feet, used in place of caltrops proper.
    • n caltrop In botany, a name of several plants. The name was applied first to the spiny heads or fruits of the plants, from their resemblance to the military instrument, and then to the plants themselves. The common caltrop or caltrops is Centaurea Calcitrapa (the star-thistle), found in waste places in the south of England. The heads are covered with long yellow spines. The name is also given to Tribulus terrestris, a plant of the Mediterranean region, with a spiny pentagonal fruit. The water-caltrop is Trapa natans, the fruit of which has several horns formed of the indurated lobes of the calyx.
    • caltrop To entangle with caltrops.
    • n caltrop In the nomenclature of the spicular elements of sponges, a tetraxial spicule having the form of a caltrop, with four equal simple smooth arms radiating from a central point.
    • n caltrop plural In entomology, the short, sharp, curved spines which occur in scattered groups in the integument of certain lepidopterous larvæ of the family Limacodidæ, and which are responsible for the urticating effect produced on the human skin by these larvæ.
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Chambers's Twentieth Century Dictionary
    • n Caltrop kal′trop an instrument armed with four spikes, so arranged that one always stands upright, used to obstruct the progress of an enemy's cavalry, or of besiegers of a fortification
    • Caltrop Also Cal′trap
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Webster's Revised Unabridged Dictionary
OE. calketrappe, calletrappe, caltor (in both senses), fr. AS. collræppe, calcetreppe, sort of thistle; cf. F. chaussetrape, star thistle, trap, It. calcatreppo, calcatreppolo, star thistle. Perh. from L. calx, heel + the same word as E. trap,. See 1st Trap


In literature:

Or to snare stags with cords and caltrops?
"Cyropaedia" by Xenophon
Sooner or later, the worm forsakes this kind of caltrop which catches on to everything.
"The Life of the Fly" by J. Henri Fabre
In vain he plunged about among the caltrops and man-traps.
"History of the United Netherlands, 1590-1599, Vol. III. Complete" by John Lothrop Motley
Argent, a caltrop proper.
"The Manual of Heraldry; Fifth Edition" by Anonymous
Caltrops spines: the branched and otherwise specialized irritating spines in Limacodid larvae.
"Explanation of Terms Used in Entomology" by John. B. Smith
The ground was carpeted with thick turf and quite free from caltrops.
"The Grandee" by Armando Palacio Valdés
And, lastly, they strewed innumerable caltrops and steel-traps upon the space between the town-moats and the camp of the besiegers.
"A Struggle for Rome, Vol. 2 (of 3)" by Felix Dahn
An hour later a message came from Mrs. Caltrop.
"The Childerbridge Mystery" by Guy Boothby

In news:

Caltrop 's Ten million years and eight minutes.
The general approach to categorizing Chapel Hill quartet Caltrop has been first to describe them as heavy metal, and then immediately to qualify that classification.
WXYC Backyard Barbecue with Caltrop , Black Skies, Fin Fang Foom.
WXYC Backyard Barbecue with Caltrop, Black Skies, Fin Fang Foom.
Let your ears wade in the sludge of North Carolina metal acts Caltrop and Black Skies.