big but useless person; all show and no substance
Idiomatic expression comparing a person to a large udo plant, which looks impressive but is too soft and inedible. Used to describe someone who is physically big or holds a high position but lacks ability or substance.
He's big, but he's just a big useless lump, good for nothing.
あの部長は独活の大木だ。
That department head is all show and no substance.
役立たず is a more direct and common word for a useless person or thing, without the nuance of being physically large or impressive-looking.
見かけ倒し means 'all show, no substance' and can apply to things or people, but lacks the specific plant metaphor and the implication of physical size.
Standard kanji spelling for this idiomatic expression.
Katakana spelling of 独活, often used for clarity or emphasis.
Kana spelling; common in casual writing.
From 独活 (udo, 'Japanese spikenard plant') + の (possessive particle) + 大木 (large tree). The udo plant grows tall and looks like a substantial tree, but its stem is soft and hollow, making it useless as timber. The phrase is used metaphorically for a person who is big or high-ranking but incompetent.