Imposter or Impostor: What’s the Difference?

Imposter or impostor? Both spellings name the same person — someone who pretends to be somebody else in order to deceive. The difference is not meaning but standing: impostor is the traditional spelling, the one listed first in the dictionaries and recommended by the style guides, while imposter is a recognised variant that has been in use for centuries and is now almost as common. In formal writing, choose impostor. In everyday writing, neither spelling will be marked wrong — but consistency matters, so pick one and stick to it.

What Does Impostor Mean?

An impostor is a noun meaning a person who pretends to be someone else, usually to deceive people or to gain something by fraud. Cambridge defines it as someone who pretends to be another person, and Merriam-Webster defines it as one who assumes a false identity. The deception is the point: an impostor is not merely mistaken about who they are, and not merely playing a role. The word carries intent — the false identity is adopted on purpose, and other people are meant to believe it.

That is why the word turns up in stories about fraud, espionage, and confidence tricks, and in everyday sentences about people who are not what they claim to be:

• “The man who claimed to be the missing heir was exposed as an impostor.”
• “She posed as a doctor for three years before the hospital discovered she was an impostor.”
• “The charity warned people not to hand money to an impostor collecting donations door to door.”

The plural is impostors. Related words keep the same -or ending: imposture is the noun for the act of deceiving in this way (“his whole career was an imposture”), though it is far less common than impostor itself.

Impostor Syndrome

The most familiar modern use of the word is in the phrase impostor syndrome — the persistent feeling, despite evident success, that you are a fraud who will be found out at any moment. The phrase is usually written with the -or spelling, and that is the form you will find in psychology books and in most newspaper and magazine writing. People who use the phrase are not accusing themselves of actual deception; they are describing the fear of being exposed as one. If you write about the topic, “impostor syndrome” is the safer and more standard form, and it is also the form most readers will expect.

What Does Imposter Mean?

Imposter means exactly the same thing as impostor. It is not a different word, a different part of speech, or a word with a narrower meaning. It is simply the alternative spelling of the same noun, and it has been around almost as long as impostor itself. The game Among Us helped make the -er spelling familiar to millions of players, but the variant long predates the game — it appears in English books from the 17th century onwards, not long after impostor entered the language.

Because the two spellings are interchangeable in meaning, the choice between them is a matter of convention and audience rather than correctness. Some writers and publications prefer imposter because it matches the pattern of other agent nouns ending in -er, such as teacher and writer. Others avoid it because dictionaries and style guides list impostor first. Neither group is making a spelling error; they are following different conventions.

What matters is that the two forms are never mixed in a single document. A report that writes “impostor” in the first paragraph and “imposter” in the third looks careless, even though each spelling is defensible on its own. Choose one, and use it throughout.

Imposter vs Impostor at a Glance

Form	Status	Meaning	Best for
impostor	Traditional and preferred spelling; dictionary headword	A person who pretends to be someone else to deceive	Formal, academic, and professional writing; “impostor syndrome”
imposter	Recognised variant spelling	Exactly the same meaning	Informal writing, and anywhere a house style prefers it

What the Dictionaries Say

Cambridge lists impostor as the headword, with “(also imposter)” given immediately beside it, and records the pronunciation as UK /ɪmˈpɒstər/ and US /ɪmˈpɑːstər/. Merriam-Webster likewise defines impostor as its main entry. The Oxford English Dictionary records impostor as the older form and imposter as a variant. No major dictionary calls imposter a misspelling, and none treats the two as different words.

The usage guides agree with the dictionaries. Garner’s Modern English Usage lists impostor as the preferred spelling, as does Fowler’s Dictionary of Modern English Usage on the British side. The Associated Press Stylebook also prescribes impostor. That is a consistent picture: impostor is the spelling that formal writing expects, and imposter is the spelling that formal writing tolerates.

Pronunciation gives no clue to the spelling, which is part of why the pair causes trouble. Both forms are pronounced identically — the final syllable is an unstressed /tər/, and the vowel in the middle is the same. You cannot hear which spelling a writer used, so the choice has to be learned rather than sounded out.

Why Are There Two Spellings?

The word came into English in the late 16th century from the French imposteur, itself from the Latin impostor, meaning one who imposes upon or deceives. English kept the Latin -or ending, which is why impostor is the older and more traditional form. The -er variant appeared almost immediately afterwards, and it has never gone away.

The reason it persists is that English has two competing patterns for nouns that name a person who does something. One pattern ends in -or: actor, doctor, inventor, impersonator. The other ends in -er: teacher, writer, builder, worker. The -er pattern is far more common, so writers have been respelling impostor as imposter for centuries, by analogy with the words they already know. The same pressure produced adviser beside advisor. Analogy is powerful, but it does not always win.

Frequency has shifted over time. Impostor has always been the more common spelling in printed books, but the gap has narrowed sharply since about 2000, and in some kinds of writing — especially online and in gaming — imposter is now about as common as impostor. That does not make impostor wrong or old-fashioned. It means the variant has become an ordinary part of the language, and a spellchecker that flags imposter is behind the dictionaries.

Which Spelling Should You Use?

For most purposes, the answer is impostor. It is the form the dictionaries list first, the form the style guides recommend, and the form your reader is most likely to expect in formal writing. It is also the form used in the set phrase “impostor syndrome”, so using it everywhere keeps your writing consistent. If you are writing an essay, a report, a job application, or anything that will be judged on correctness, impostor is the safer choice, and it costs nothing.

Use imposter only when you have a reason: your publication’s house style prefers it, you are quoting a source that uses it, or you are writing in a casual context where the variant is normal, such as a gaming forum. The word is not wrong, so there is no need to correct it when you meet it in other people’s writing — but there is also no advantage in choosing it over impostor unless a style guide tells you to.

A useful memory hook is the family resemblance: impostor ends in -or like actor and impersonator, and an impostor is, in a sense, an actor playing a part they have no right to. If you can remember impersonator, you can remember impostor.

Correct vs Incorrect

Correct	Incorrect / avoid	Why
“The police arrested the impostor.”	“The police arrested the imposter.” (in formal writing)	Imposter is a variant, not the preferred form in formal writing.
“She struggled with impostor syndrome.”	“She struggled with imposter syndrome.” (in formal writing)	The set phrase is conventionally written with -or.
“He was an imposter in the game.” (casual)	“He impostered his way into the job.”	There is no verb to imposter; use “he posed as” or “he impersonated”.
“Two impostors were caught.”	“Two imposters were caught.” (in formal writing)	Same rule for the plural: prefer impostors in formal writing.

Common Mistakes

The most common mistake is assuming that one of the two spellings is simply wrong. It is not. A teacher who marks imposter as a spelling error is applying a rule the dictionaries do not support, and a writer who insists that impostor is outdated is ignoring the style guides. Both spellings are legitimate; they differ in status, not in correctness.

A second mistake is treating the word as an adjective. Impostor is a noun only. You can write “an impostor doctor”, where the noun modifies another noun, but you cannot write “his impostor behaviour” and expect it to work the same way — “fraudulent” or “deceptive” is what that sentence needs.

A third mistake is confusing an impostor with a lookalike. A doppelgänger is someone who happens to look like another person; an impostor deliberately pretends to be that person. Resemblance is an accident. Imposture is a choice.

Frequently Asked Questions

Is it imposter or impostor?

Both are correct. Impostor is the traditional and preferred spelling, listed first in Cambridge and Merriam-Webster and recommended by the major style guides. Imposter is a recognised variant with the same meaning. In formal writing, use impostor.

Is imposter a real word?

Yes. Imposter is listed in the dictionaries as a variant of impostor, and it has been in use since the 17th century. It is not a misspelling, a slang form, or a modern invention, though it is less common than impostor in formal writing.

What is the difference between an impostor and a fraudster?

An impostor is a specific kind of fraudster: one whose fraud depends on pretending to be someone else. Not every fraudster is an impostor — a person can commit fraud without assuming a false identity — but every impostor is deceiving people about who they are.

Is it impostor syndrome or imposter syndrome?

The standard form is impostor syndrome. That is the spelling used in most psychology writing and in the dictionaries’ examples. “Imposter syndrome” is widely understood and often seen online, but in formal writing the -or form is the better choice.

How do you pronounce impostor?

UK /ɪmˈpɒstə/ (im-POS-tuh) and US /ɪmˈpɑːstər/ (im-POS-tuhr). The stress falls on the second syllable, -pos-, and the spelling makes no difference to the sound.

Takeaway

Impostor and imposter are the same word in two spellings. Impostor is the traditional form, the dictionary headword, and the spelling the style guides recommend — so it is the one to use in formal writing and in the phrase “impostor syndrome”. Imposter is a genuine variant, not an error, and it is fine wherever a house style or a casual context accepts it. Whichever you choose, use it consistently, and remember the hook: an impostor is an actor of sorts, and like actor and impersonator, it ends in -or.

Sources: Cambridge Dictionary, “impostor” — dictionary.cambridge.org/us/dictionary/english/impostor.