What does caltrap mean?
A caltrap is a small, usually four-pointed metal device designed to be scattered across the ground as an anti-cavalry and anti-personnel obstacle. Because of its shape, however it lands one sharp point projects upward, ready to pierce a horse's hoof, a soldier's foot, or later a vehicle tyre. Caltraps were used from antiquity through the Middle Ages and remain familiar in military history and museum collections. By extension, the name was given to certain plants whose spiny seed pods closely resemble the weapon, notably puncturevine (Tribulus terrestris) and water chestnuts of the genus Trapa — burrs notorious for flattening tyres and injuring bare feet. The word is now chiefly historical and technical, appearing in accounts of siege warfare, archaeology, and botany, and it carries connotations of cunning, low-tech defence: a cheap weapon that needs no soldier to wield it once thrown. An alternate, now less common spelling is caltrop.
A spiked metal device scattered on the ground so one point always faces upward, used to impede cavalry, infantry, or vehicles.
"The moat's approaches were strewn with caltraps to break any charge."
Most often encountered in historical and military-history writing.
Any of several plants with spiny fruits resembling the weapon, especially Tribulus terrestris and water chestnuts of the genus Trapa.
"The pasture was infested with caltrap burrs that punctured every tyre crossing it."
In botanical usage the spelling caltrop is more common.
Regular plural; caltraps were always deployed in numbers, so the plural is the commoner form in practice.
"Sacks of iron caltraps were carried with the army's baggage."
Scatter enough four-pointed caltraps and it doesn't matter which way they land — one spike always points up, ready to pierce a hoof, boot, or tire.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of caltrap
Caltrap comes from Old English calcatrippe, meaning a device that 'catches the heel', borrowed from Medieval Latin calcatrippa, formed from Latin calcare ('to tread', from calx, 'heel') plus a second element related to trapping. The word has been in English since at least the early Middle Ages, and the spelling caltrop became standard later. Its Latin root calx also gives English words such as calcium, calculus, and recalcitrant (literally 'kicking back'), making these distant relatives.
Related word forms
How caltrap is actually used
The word is largely historical and technical today, appearing mainly in discussions of medieval warfare, archaeology, and botany. In botanical contexts 'caltrop' is the more usual spelling for both the weapon and the plants named after it. The plural is regular.
Easily confused with caltrap
Caltrop is simply the more common modern spelling of the same word; 'caltrap' is an older or alternate form with identical meaning.
Catnip is an aromatic herb in the mint family that attracts cats, whereas a caltrap is either a spiked military obstacle or a spiny-fruit plant.