The word "腐朽" is formed by combining the characters "腐" and "朽". "腐" signifies decay and is composed of the radical "肉" (meat) indicating organic decay, with "府" serving as a phonetic component. "朽" denotes rot and is composed of the radical "木" (wood) indicating decay in wood, with "丂" as a phonetic element. Together, they form a compound word where both characters contribute semantically to mean "decayed" or "rotten".