Final answer:
Frank Lloyd Wright extensively used the cantilever, a beam or slab extended significantly to merge indoor and outdoor spaces, notably in his design of the Falling water house.
Step-by-step explanation:
Frank Lloyd Wright extensively used the cantilever, a beam or slab extended a substantial distance beyond its supporting wall, to unite indoor and outdoor spaces. This architectural feature allowed Wright to create buildings that were in harmony with the environment, providing open floor plans and a seamless transition between the interior and exterior. One of the most famous examples of Wright's use of cantilevered design is the iconic Falling water house, where terraces extend out over a waterfall, integrating the home with its natural surroundings.