Infeasible Or Unfeasible: Which Word Is Correct?

Infeasible Or Unfeasible often causes confusion because both words appear in English writing. Both forms can mean that something cannot work or cannot be done successfully. However, infeasible is the more established and widely preferred choice. Unfeasible also appears in dictionaries and real-world usage, but it is less common.

The two words share the same basic idea of something being impractical or impossible to achieve. You may see these terms in business plans, engineering reports, academic writing, and project discussions.

Choosing the right word can make your writing sound clearer and more professional. In most formal situations, infeasible is the safer choice. This guide explains the difference between infeasible and unfeasible, their meanings, origins, usage, common mistakes, and everyday examples. It also gives you an easy trick for remembering which word to use.

Quick Answer

Infeasible is the preferred and more common word. It means impossible or impractical to achieve.

Unfeasible has the same general meaning but is less common.
Example: The original project plan was infeasible because of its high cost.

Meaning of Infeasible

Infeasible means impossible, impractical, or unlikely to succeed.

It describes something that cannot reasonably be done because of limits such as time, money, resources, or technology.

Examples

1. The engineers decided that the original design was infeasible.
2. Building the bridge within two weeks would be infeasible.

Common Uses of Infeasible

You may use infeasible when discussing:

• business plans
• engineering projects
• budgets
• schedules
• technology
• research
• construction
• proposed solutions

Simple meaning:

👉 Infeasible = Not practical or not possible to achieve.

Meaning of Unfeasible

Unfeasible also means impractical, impossible, or difficult to accomplish.

It uses the prefix un- with feasible.

Although dictionaries recognize the word, many writers prefer infeasible in formal contexts.

Examples

1. The proposed schedule seemed unfeasible for the small team.
2. The company rejected the unfeasible plan.

Common Uses of Unfeasible

You may encounter unfeasible in:

• everyday writing
• informal discussions
• business communication
• online content
• general descriptions

Simple meaning:

👉 Unfeasible = Not feasible or practical.

Key Differences: Infeasible vs Unfeasible

Feature	Infeasible	Unfeasible
Meaning	Not practical or possible	Not practical or possible
Tone	Formal and professional	General and less formal
Usage	Academic, technical, business	General and informal contexts
Popularity	More common	Less common
Word formation	Latin-based negative prefix	English negative prefix
Preferred choice	Usually preferred	Acceptable but less common

Quick Comparison

Infeasible: The plan is infeasible because it exceeds the budget.

Unfeasible: The plan is unfeasible because it exceeds the budget.

Both sentences communicate the same basic idea. Infeasible sounds more standard in formal writing.

Origin & History

Feasible comes from the French word faisable, meaning capable of being done. It ultimately relates to the Latin verb facere, meaning “to make” or “to do.”

Infeasible developed by adding the negative prefix in-.

Unfeasible developed by adding the English negative prefix un-.

English often uses different prefixes to create negative forms.

Similar Word Examples

• feasible / infeasible
• possible / impossible
• practical / impractical
• legal / illegal
• regular / irregular
• effective / ineffective

These examples show how English uses different prefixes to create opposite meanings.

🇬🇧 British English vs 🇺🇸 American English Spelling

Infeasible and unfeasible can appear in both British and American English.

There is no major spelling difference between the two varieties.

However, infeasible is generally the safer choice for formal writing in either variety.

British vs American English Comparison

Feature	British English	American English
Preferred term	Infeasible	Infeasible
Alternative	Unfeasible	Unfeasible
Spelling	Same	Same
Meaning	Same	Same
Formal choice	Infeasible	Infeasible

When to Use Infeasible

Use infeasible when you want a clear and professional term for something that cannot reasonably be achieved.

It works especially well in technical, academic, and business writing.

Examples

• The proposed solution is infeasible due to limited resources.
• The deadline makes the project infeasible.
• The engineers considered the design infeasible.
• The plan became infeasible after costs increased.

Best Choice for Formal Writing

Choose infeasible when writing:

• reports
• academic papers
• business proposals
• technical documents
• professional emails
• research studies

When to Use Unfeasible

Use unfeasible when you want to express that something is not feasible.

It is understandable and recognized, but it is less common than infeasible.

Examples

• The proposed timeline is unfeasible.
• They considered the plan unfeasible.
• The project became unfeasible after funding was reduced.
• That solution seems unfeasible for a small business.

Important Note

You will rarely need unfeasible if infeasible already fits your sentence.

When in doubt, choose infeasible.

Common Mistakes

Mistake 1: Assuming Unfeasible Is Always Wrong

❌ Unfeasible is never a real English word.

✅ Unfeasible is recognized, but infeasible is more common.

The issue involves preference and frequency, not simple correctness.

Mistake 2: Using Infeasible When You Mean Difficult

❌ The task is infeasible because it requires extra effort.

✅ The task is difficult because it requires extra effort.

Infeasible suggests that something cannot reasonably be achieved.

Mistake 3: Using Both Words Together

❌ The project is infeasible and unfeasible.

✅ The project is infeasible.

Using both creates unnecessary repetition.

Mistake 4: Choosing Unfeasible in Formal Writing

❌ The research team described the proposal as unfeasible.

✅ The research team described the proposal as infeasible.

Infeasible is usually the stronger choice for formal contexts.

Mistake 5: Confusing Feasible With Infeasible

❌ The plan is feasible because it cannot be completed.

✅ The plan is infeasible because it cannot be completed.

Feasible means possible or practical.

Infeasible means not possible or practical.

Easy Trick to Remember

Think of the word feasible first.

Feasible = Possible

Then remember:

Infeasible = Not feasible

The prefix in- often creates a negative meaning.

For example:

• complete → incomplete
• effective → ineffective
• visible → invisible
• feasible → infeasible

Memory Tip

👉 Feasible = Can do

👉 Infeasible = Cannot reasonably do

If you want the most standard formal option, choose infeasible.

Everyday Life Examples

1. Business Planning

Businesses often reject plans that require too much money.

Example:
The expansion plan became infeasible after construction costs increased.

• Primary keyword: infeasible
• Secondary keyword: infeasible plan

2. Project Deadlines

A short deadline can make a project impossible to complete.

Example:
Finishing the entire project in one day would be infeasible.

• Primary keyword: infeasible
• Secondary keyword: infeasible deadline

3. Engineering

Engineers assess whether designs can work safely and efficiently.

Example:
The engineers decided that the original design was infeasible.

• Primary keyword: infeasible
• Secondary keyword: infeasible design

4. Personal Plans

People can describe unrealistic plans as unfeasible.

Example:
Driving across the country in three hours is unfeasible.

• Primary keyword: unfeasible
• Secondary keyword: unfeasible plan

5. Academic Research

Researchers may reject ideas that lack enough resources.

Example:
The research team found the proposed experiment infeasible.

• Primary keyword: infeasible
• Secondary keyword: infeasible research

Related Keywords

Here are useful keyword variations for this topic:

• infeasible or unfeasible
• infeasible vs unfeasible
• unfeasible vs infeasible
• infeasible meaning
• unfeasible meaning
• is unfeasible a word
• is infeasible correct
• infeasible definition
• unfeasible definition
• feasible vs infeasible

Google Trends & Usage Data

Search interest for infeasible usually comes from academic, technical, and professional contexts.

Unfeasible attracts spelling and word-choice searches because users question its standard usage.

Interest can differ across the USA, UK, Australia, India, and Pakistan.

For SEO, targeting both forms helps capture comparison and spelling-related searches.

Usage Insight by Country

Country	Common Search Context	SEO Insight
🇺🇸 USA	Business and technical writing	Lead with infeasible
🇬🇧 UK	Academic and professional English	Explain both forms
🇦🇺 Australia	General and professional English	Target comparison terms
🇮🇳 India	English learning and academics	Use simple definitions
🇵🇰 Pakistan	English learning and formal writing	Include spelling guidance

Key SEO Insight

Infeasible or unfeasible has strong comparison and spelling intent.

Infeasible meaning targets users seeking a direct definition.

Unfeasible meaning targets users checking whether the alternative is valid.

Using both terms naturally can capture several related search queries.

📊 Comparison Table: Keyword Variations

Keyword Variation	Search Intent	Best Content Angle
infeasible or unfeasible	Comparison	Spelling guide
infeasible vs unfeasible	Comparison	Word difference
unfeasible vs infeasible	Comparison	Usage guide
infeasible meaning	Informational	Definition
unfeasible meaning	Informational	Definition
is unfeasible a word	Informational	Correctness
is infeasible correct	Informational	Grammar
infeasible definition	Informational	Vocabulary
unfeasible definition	Informational	Vocabulary
feasible vs infeasible	Comparison	Opposite meanings

FAQ’s

1. Is “unfeasible” a correct word?

Yes. Unfeasible is a recognized word. However, infeasible is more common and usually preferred.

2. What is the difference between infeasible and unfeasible?

Both generally mean not practical or possible. Infeasible is more established and common in formal writing.

3. Which is more common, infeasible or unfeasible?

Infeasible is more common. It is usually the better choice for professional and academic writing.

4. Is infeasible more formal than unfeasible?

Yes. Infeasible generally sounds more standard and formal. It fits technical and professional contexts well.

5. Why does confusion between infeasible and unfeasible exist?

Both words use a negative prefix with feasible. Their meanings overlap, which makes the choice confusing.

Conclusion

Infeasible Or Unfeasible can create uncertainty for English writers. Both words describe something that is not practical or possible. However, infeasible is the more common and established choice. It works especially well in academic, technical, business, and professional writing. Unfeasible also exists and can communicate the same basic idea.

Yet, it appears less frequently and may sound less natural to some readers. The easiest choice is therefore infeasible. Think of feasible as something that can be done. Adding in- creates the opposite meaning. For example, an infeasible project cannot reasonably meet its requirements. Always consider the context before choosing your word. When you want the safest formal option, choose infeasible.