Ask Difference

Unsubstantial vs. Insubstantial — What's the Difference?

By Maham Liaqat & Fiza Rafique — Updated on March 7, 2024
Unsubstantial often implies lack of physical presence or solidity, while insubstantial suggests inadequacy or lack of significance.
Unsubstantial vs. Insubstantial — What's the Difference?

Difference Between Unsubstantial and Insubstantial


Key Differences

Unsubstantial typically refers to something that lacks a solid, physical form or substance, often implying something is not real or tangible. Whereas, insubstantial is used to describe something that is not substantial or significant in terms of size, value, or importance. It suggests that something is too slight or minor to be of importance.
Unsubstantial can describe things that are not only lacking in physical form but also in essence or depth, suggesting something is superficial or not fully developed. On the other hand, insubstantial often focuses on the lack of material strength, weight, or solidity, indicating that something is fragile, lightweight, or of poor quality.
In literary or philosophical contexts, unsubstantial may be used to describe concepts, ideas, or entities that lack depth, reality, or permanence, emphasizing their ephemeral or illusory nature. In contrast, insubstantial can describe arguments, evidence, or reasons that are weak, insufficient, or unconvincing, lacking in solidity or persuasiveness.
The term unsubstantial might also be applied in discussions about morality or ethics, where it could denote actions or characteristics lacking in substance or virtue. Insubstantial, meanwhile, might be used to signify the trivial or negligible impact of certain actions or decisions, highlighting their lack of meaningful consequences.
In everyday usage, unsubstantial could describe objects, structures, or physical entities that are perceived as lacking in heft or durability. Insubstantial, however, often pertains to qualitative assessments of value, importance, or efficacy, suggesting that something does not meet expected standards or requirements.

Comparison Chart

Primary Implication

Lack of physical presence or solidity
Lack of significance or material strength

Common Usage

Describes something not real or tangible
Describes something minor or of poor quality

Contextual Focus

Essence, depth, or reality
Material strength, weight, or persuasiveness

Philosophical Connotation

Ephemeral or illusory nature
Weak or unconvincing arguments or evidence

Everyday Significance

Lacking in heft or durability
Lacking expected standards of value or impact

Compare with Definitions


Lacking depth or seriousness.
The discussion remained unsubstantial, barely scratching the surface of the topic.


Lacking material strength or solidity.
The insubstantial fabric tore easily under pressure.


Ephemeral or fleeting.
The beauty of the moment was unsubstantial, fading as quickly as it had appeared.


Fragile or lightweight.
The bridge's insubstantial construction raised safety concerns.


Lacking solidity.
The ghost appeared as an unsubstantial form in the dimly lit room.


Lacking in substance or content.
The article was criticized for being insubstantial and lacking depth.


Not real or tangible.
Her dreams of flying felt unsubstantial in the harsh light of day.


Minor or negligible impact.
The changes to the law were insubstantial and did not address the main issues.


Superficial or shallow.
The movie's plot was criticized for being unsubstantial.


Not significant in amount or value.
The evidence provided was insubstantial and unconvincing.


Lacking material substance; insubstantial.


Not firm or solid; weak or flimsy
A shed made of insubstantial materials.


Lacking firmness or strength; flimsy.


Very small or negligible, as in importance, size, or amount
An insubstantial volume of traffic.


Lacking basis in fact.


Lacking or appearing to lack substance or reality
"the insubstantial vapor of an autumn field" (Loren Eiseley).


(archaic) Insubstantial.


Lacking substance; not real or strong.
The bridge was insubstantial and would not safely carry a car.


Lacking in matter or substance; visionary; chimerical.


Unsubstantial; not real or strong.


Lacking material form or substance; unreal;
As insubstantial as a dream
An insubstantial mirage on the horizon


Lacking material form or substance; unreal;
As insubstantial as a dream
An insubstantial mirage on the horizon


Lacking in nutritive value;
The jejune diets of the very poor

Common Curiosities

Can something be both unsubstantial and insubstantial?

Yes, something can be both unsubstantial and insubstantial if it lacks physical substance and is also of little significance or importance.

How is unsubstantial used in a sentence?

"The argument felt unsubstantial, lacking the depth needed to convince."

How is insubstantial used in a sentence?

"The evidence was insubstantial, making it difficult to draw a firm conclusion."

Can ideas be unsubstantial?

Yes, ideas can be considered unsubstantial if they lack depth, essence, or practicality.

What does unsubstantial mean?

Unsubstantial refers to something lacking a solid, physical form or substance, often implying it is not real or tangible.

Is unsubstantial always negative?

Not always, but it often carries a negative connotation by implying something lacks depth, reality, or permanence.

How is insubstantial different from unsubstantial?

Insubstantial often describes something not substantial or significant in terms of size, value, or importance, while unsubstantial implies a lack of physical presence or solidity.

Is insubstantial a critique of quality?

Yes, describing something as insubstantial often critiques its quality, suggesting it is fragile, lightweight, or of poor significance.

Is insubstantial the same as insignificant?

Not exactly, but both terms suggest a lack of importance or impact, with insubstantial specifically highlighting a lack of material substance or convincing evidence.

What makes something insubstantial?

Lack of material strength, significance, persuasiveness, or solidity can make something insubstantial.

Can unsubstantial refer to physical objects?

Yes, unsubstantial can describe physical objects that lack heft or durability.

How do unsubstantial and insubstantial relate to arguments?

An unsubstantial argument lacks depth or seriousness, whereas an insubstantial argument lacks convincing evidence or strength.

Can a feeling be described as unsubstantial?

Yes, feelings can be described as unsubstantial if they are fleeting, not based on solid reality, or lack depth.

What is an example of insubstantial food?

A meal considered insubstantial may be light and not filling, lacking in nutritional value or quantity.

Can unsubstantial be positive?

It can be, especially in contexts where being light, ephemeral, or not overly serious is beneficial or desired.

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Author Spotlight

Written by
Maham Liaqat
Co-written by
Fiza Rafique
Fiza Rafique is a skilled content writer at, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.

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