MEANING: noun:
1. A device with (typically) four projecting spikes arranged in a way that one spike is always pointing up. Used to obstruct the passage of cavalry, vehicles, etc.
2. Any of various plants having spiny fruits.

ETYMOLOGY: From Old English calcatrippe (any of various plants, such as thistle, that catch the feet), from Latin calcatrippa (thistle), from calx (heel) + trap. Earliest documented use: 1000.

CALSTROP - a leather belt used to sharpen California

CALTROOP - a squad of the California National Guard

CALDROP - what will happen when the San Andreas Fault finally splits wide open and the western part of the state falls into the Pacific