The term for a geological fault that serves as the boundary between two tectonic plates is a transform fault. This type of fault occurs when two plates slide past each other horizontally, leading to seismic activity. Notable examples include the San Andreas Fault in California. Unlike convergent or divergent boundaries, transform faults can create significant earthquakes, as stress builds when the plates become stuck due to friction. Understanding these faults is crucial for predicting seismic events and ensuring safety in areas prone to earthquakes.