無駄
むだ · muda · JLPT N3 · noun
futility
🗑️ 無 without + 駄 packhorse load = a load carried for nothing; futile
駄 is a packhorse's load and, by extension, something cheap or worthless. You also see it in 駄目 (dame, no good). Sound hook: muda sounds like mud-a, effort that sinks into the mud and gets you nowhere.