1. a device with four spikes arranged so that one always points upward, historically scattered on the ground to injure the feet of enemies or puncture tires
Usage: also spelled caltrops (plural); historical military device
2. any of various plants with spiky seed pods or fruits, especially those of the genus Tribulus
Usage: botanical term

Examples

• Medieval soldiers scattered caltraps across the battlefield to slow down the enemy cavalry.
• The road was littered with caltraps that could puncture vehicle tires.
• Caltraps with their sharp spikes were designed to be difficult to remove quickly.
• The caltrap plant grows in arid regions and produces seeds with dangerous thorns.
• Hikers in the desert must watch out for caltraps hidden in the sand.