The word "灿烂" is formed by combining two characters, each containing the "火" (fire) radical, linking them to concepts of light and brightness. "灿" incorporates "火" with "山" to denote luminosity, while "烂" combines "火" with "兰" to convey radiance. Together, they create a compound where both characters semantically emphasize brilliance, resulting in the meaning of splendid or radiant.