Mistakingly or Mistakenly: Which Is Correct?

Sometimes, a single extra syllable can make an otherwise simple word feel confusing. Mistakingly or mistakenly is one of those spelling and usage questions that often causes hesitation, especially because both forms seem as though they should be related to the verb mistake.

The standard and widely accepted word is mistakenly. Mistakingly does exist in some dictionaries and historical usage, but it is uncommon and generally not the preferred choice in modern standard English. If you’re writing an email, essay, article, or professional document, mistakenly is the safer and more natural option.

Mistakingly or Mistakenly: Which Is Correct?

If you’re choosing between mistakingly or mistakenly, use:

Mistakenly 

For example:

“I mistakenly sent the email to the wrong person.”

The form mistakingly is much less common. Although it has appeared in English usage, most modern writers would choose mistakenly instead.

So, when you want to say that something happened because of a mistake, mistakenly is the natural choice.

What Does Mistakenly Mean?

Mistakenly is an adverb meaning incorrectly, unintentionally, or as a result of a mistake.

It comes from the adjective mistaken, which means wrong or incorrect.

For example:

“She mistakenly believed that the meeting was on Friday.”

This means she believed the meeting was on Friday, but that belief was incorrect.

Another example is:

“The package was mistakenly delivered to the wrong address.”

Here, the delivery happened unintentionally or because of an error.

Common meanings of mistakenly

Depending on the sentence, mistakenly can mean:

• By accident
• In error
• Incorrectly
• Unintentionally
• Because of a misunderstanding

The exact meaning depends on the context.

Why Is “Mistakenly” More Common?

The difference becomes easier to understand when you look at the word’s structure.

Mistakenly comes from mistaken + -ly.

The adjective mistaken is already an established form:

mistaken → mistakenly

Compare it with other words:

• accidental → accidentally
• intentional → intentionally
• mistaken → mistakenly
• careful → carefully

By contrast, mistakingly appears to be formed directly from the present participle mistaking, which is not the usual basis for this adverb.

That is why mistakenly sounds more natural to most English speakers.

Is “Mistakingly” a Real Word?

This is where the question gets interesting.

Mistakingly has been used in English, and some dictionaries recognize it. However, it is relatively rare compared with mistakenly.

In practical modern writing, there is little reason to choose mistakingly when mistakenly communicates the idea clearly and naturally.

For example:

“He mistakenly deleted the file.”

This is standard and immediately familiar.

You could encounter mistakingly in older, unusual, or less common writing, but it is not the form most people expect in contemporary English.

A useful rule

If you’re unsure, use:

mistakenly

It is the conventional choice and works well in both everyday and formal writing.

Mistakingly vs Mistakenly Examples

Looking at the two words side by side can make the distinction clearer.

Mistakenly

• I mistakenly deleted the message.
• She mistakenly thought the store was closed.
• He was mistakenly identified as the person responsible.
• The payment was mistakenly sent to another account.
• I mistakenly entered the wrong password.

These sentences sound natural in modern English.

Mistakingly

Although mistakingly can be found in some English sources, it is uncommon:

“He mistakingly assumed that everyone agreed.”

Most modern writers would instead write:

“He mistakenly assumed that everyone agreed.”

The second version is much more natural.

How to Use “Mistakenly” Correctly

Because mistakenly is an adverb, it usually modifies a verb or describes how an action happened.

Before a verb

“She mistakenly entered the wrong address.”

After a verb

“She entered the wrong address mistakenly.”

The first sentence is much more natural in ordinary English.

With beliefs and assumptions

Mistakenly is especially common when describing an incorrect belief, assumption, identification, or interpretation.

Examples include:

• He mistakenly believed the information was accurate.
• She mistakenly assumed that the appointment had been canceled.
• They mistakenly identified the building.
• I mistakenly thought you had already left.

Mistakenly vs Accidentally

These words are closely related, but they’re not always interchangeable.

Mistakenly emphasizes an error or incorrect understanding.

“I mistakenly used the wrong file.”

Accidentally emphasizes that something happened unintentionally.

“I accidentally deleted the file.”

Sometimes either word works:

“I mistakenly sent the message.”

“I accidentally sent the message.”

But the emphasis changes slightly. Mistakenly suggests an error in judgment or understanding, while accidentally focuses more directly on the lack of intention.

Mistakenly vs Incorrectly

These words can also overlap.

Incorrectly generally means that something was done or understood in the wrong way.

“The form was incorrectly completed.”

Mistakenly often suggests that the person made an error because they believed something that wasn’t true.

“She mistakenly believed that the form was optional.”

The distinction isn’t always dramatic, but understanding it can help you choose the more precise word.

Common Mistakes With Mistakenly

1. Writing “mistakingly” in formal work

While the word can be encountered, mistakenly is usually the better choice for standard modern writing.

2. Confusing “mistaken” and “mistaking”

These words have different roles.

Mistaken usually describes someone or something that is wrong:

“I was mistaken.”

Mistaking is the present participle of mistake:

“She is mistaking one person for another.”

From mistaken, we get the common adverb:

mistakenly

3. Assuming every adverb uses the “-ingly” pattern

English doesn’t always create adverbs by simply adding -ly to an -ing form.

That’s why the natural expression is:

mistakenly

rather than the much less common:

mistakingly

Quick Comparison: Mistakingly vs Mistakenly

Word	Common in modern English?	Recommended?	Meaning
mistakenly	Yes	Yes	In error or incorrectly
mistakingly	Rare	Usually no	Intended to mean incorrectly

For everyday, academic, business, and professional writing, mistakenly is the clear choice.

Frequently Asked Questions

Is it mistakingly or mistakenly?

Mistakenly is the standard and preferred form in modern English. Mistakingly exists in some usage and dictionaries but is uncommon.

Is “mistakingly” grammatically correct?

It can be found as an English word, but it is rare. In most situations, mistakenly is the more natural and widely accepted choice.

What does mistakenly mean?

Mistakenly means incorrectly, unintentionally because of an error, or as a result of a mistaken belief or understanding.

What is the difference between mistakenly and accidentally?

Mistakenly emphasizes an error or incorrect understanding, while accidentally emphasizes that something happened without intending it.

Can I use mistakenly in formal writing?

Yes. Mistakenly is perfectly appropriate for formal, academic, professional, and everyday writing.

Is “mistakenly” an adverb?

Yes. Mistakenly is an adverb because it describes how an action was performed or how something happened.

What is the adjective form of mistakenly?

The related adjective is mistaken.

For example:

“I was mistaken about the date.”

From this adjective, we get:

mistaken → mistakenly

Conclusion: Mistakingly or Mistakenly?

When you’re deciding between mistakingly or mistakenly, the best choice for modern standard English is mistakenly.

It means doing something incorrectly, making an error, or acting based on a mistaken belief. Although mistakingly can be found in some sources, it is uncommon and may sound awkward to many readers.

The easiest rule to remember is simple:

mistaken → mistakenly

So, if you’re writing a sentence such as “I ___ sent the wrong file,” the natural answer is mistakenly.

When in doubt, choose the familiar standard form: mistakenly.