The term caltrop refers to a type of spiked metal object that is used for defending against enemy cavalry or puncturing automobile tires. Its first appearance in English was in 1300, spelled as calketrap. Other variations over time include calcatrippe, caltroppe, calltrop, calthrap, galtroppe, and more. Even today, there is no standardized spelling, with caltrap, galtrop, galthrap, galtrap, and calthrop all recognized by different authors. The term originates from the Medieval Latin word calcatrippa, meaning “thistle”. This is derived from calx, meaning “heel” (also related to words like calcium, calculation, and causeway), and trappa, meaning “trap”. Calx likely influenced by the verb calcare (“to tread”), comes from the Ancient Greek khalix, meaning “pebble”, while trappa traces back to the Proto-Indo-European root dremb, meaning “to run”.
