Translation guide
Describes something lacking physical substance, solidity, or importance. Japanese uses different words for physical thinness, lack of evidence, and insignificance.
Describing objects, structures, or materials that are thin, flimsy, or not solid.
Common word for something physically thin and flimsy, often with a negative nuance of being cheap or poorly made.
この壁は薄っぺらくて、隣の声が丸聞こえだ。
This wall is so insubstantial that I can hear everything from next door.
Literally 'without substance', used for things that lack physical reality, like ghosts or illusions.
幽霊は実体のない存在だ。
Ghosts are insubstantial beings.
Means 'thin' or 'sparse', used for gases, atmospheres, or abstract things like presence. More formal/literary.
山頂の空気は希薄で、存在感も希薄になる。
The air at the summit is thin, and one's presence feels insubstantial.
Describing arguments, evidence, or claims that are weak, unconvincing, or not well-founded.
Literally 'thin in basis', the most natural way to say an argument or claim is insubstantial or lacks solid evidence.
その主張は根拠が薄くて、誰も信じなかった。
The claim was insubstantial and no one believed it.
Formal word meaning 'weak' or 'feeble', often used for arguments or evidence. Common in written or academic contexts.
彼の反論は薄弱で、裁判では通用しなかった。
His rebuttal was insubstantial and didn't hold up in court.
Means 'unconvincing', a common way to describe an insubstantial argument. Focuses on lack of persuasive power.
彼の説明は説得力がなく、誰も納得しなかった。
His explanation was insubstantial and convinced no one.
Describing things that are trivial, negligible, or not worth considering.
Common phrase meaning 'trivial' or 'insignificant'. Used for matters, amounts, or people considered unimportant.
そんな取るに足らない問題で喧嘩するな。
Don't fight over such an insubstantial issue.
Means 'trivial' or 'minor', very common for small, insignificant matters.
些細な違いにこだわる必要はない。
There's no need to obsess over insubstantial differences.
A phrase meaning 'it's not a big deal', used to downplay something as insubstantial or unimportant.
そのミスは大したことではないから、気にしないで。
That mistake is insubstantial, so don't worry about it.
Describing people, works, or ideas that are shallow, empty, or lack depth.
Literally 'without content', used for people, books, speeches, etc. that are insubstantial or shallow.
彼の話は中身がなくて、退屈だった。
His talk was insubstantial and boring.
Means 'empty' or 'hollow', often used for feelings or abstract concepts. More literary.
その映画は映像は美しいが、内容は空虚だ。
The movie has beautiful visuals but its content is insubstantial.
Means 'frivolous' or 'shallow', often describing a person's character or attitude. Can be negative.
彼の軽薄な態度に腹が立った。
I was annoyed by his insubstantial attitude.
There is no single Japanese word that covers all senses of 'insubstantial'. Always choose based on whether you mean physically thin, lacking evidence, unimportant, or shallow. Using the wrong word can sound unnatural.
薄っぺらい議論
insubstantial argument (unnatural; use 根拠の薄い instead)