Definition of "nonagonal" []

• Having nine sides and nine angles (adjective)

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• "The structure itself is a pure white nonagonal building, of original and unique design, rising from a flight of white stairs encircling its base; and surmounted by a majestic and beautifully proportioned dome, bearing nine tapering symmetrically placed ribs of decorative as well as structural significance, which soar to its apex and finally merge into a common unit pointing skyward."