朽ちる
くちる · kuchiru · JLPT N1 · noun
putrefaction
🪵 朽 contains the tree radical 木, because rot is what happens to wood left out over time
The kanji 朽 uses 木 (tree) as its radical, since decay is mainly what happens to wood. 朽ちる describes old buildings and fallen logs that slowly crumble away.