Passersby vs passerby is a common English spelling and grammar question. Both passerby and passersby are correct, but they are used differently. The main difference is number: passerby is singular, while passersby is plural.
If you are talking about one person who passes by, use passerby. If you are talking about two or more people who pass by, use passersby.
- One person: a passerby
- Two or more people: passersby
For example:
A passerby helped the injured cyclist.
Several passersby stopped to watch the performance.
Understanding this distinction is important because passerby is an unusual compound noun. Instead of simply adding -s to the end, its plural form is passersby.
Passerby: Singular Form
Passerby is the singular form of the noun. It refers to one person who happens to be passing a particular place.
The word is made from two parts:
- passer — a person who passes
- by — past or alongside a place
Together, passerby describes a person who passes by a location, usually without being directly involved in what is happening there.
Examples of passerby
- A passerby called the police after seeing the accident.
- A passerby offered directions to the tourists.
- The injured man asked a passerby for help.
- A passerby noticed the lost wallet.
- The artist asked a passerby to look at the painting.
- One passerby stopped to admire the street musician.
Notice that each sentence refers to one person.
You can usually identify the singular form by looking at words such as a, an, one, or the before the noun.
For example:
A passerby noticed the problem.
Here, a passerby clearly means one person.
Passersby: Plural Form
Passersby is the plural form of passerby. It refers to two or more people who are passing by.
Examples include:
- Several passersby stopped to help.
- The loud noise attracted many passersby.
- Two passersby witnessed the incident.
- The street performer entertained dozens of passersby.
- Several passersby looked up when they heard the announcement.
- Police questioned the passersby who had seen the accident.
The important point is that the plural -s is added to passer, not to by.
That is why the correct plural is:
passersby
not:
passer-bys
and not:
passerbys
Passersby vs Passerby: The Main Difference
The simplest way to understand passersby vs passerby is to remember that the two forms indicate different numbers.
| Word | Number | Meaning | Example |
|---|---|---|---|
| passerby | Singular | One person passing by | A passerby called for help. |
| passersby | Plural | Two or more people passing by | Several passersby called for help. |
The difference is similar to other nouns that have an unusual plural structure.
For example:
- mother-in-law → mothers-in-law
- attorney general → attorneys general
- passerby → passersby
The part that represents the main noun receives the plural ending.
Is Passerby One Word?
Yes. Passerby is normally written as one word when it is used as a noun.
Correct:
A passerby helped the child.
Incorrect:
A passer by helped the child.
In modern standard English, passerby is the standard noun form for a person who passes by.
You may occasionally encounter passer-by, especially in older writing or certain style traditions, but passerby is the common modern spelling in American English.
For a US-English website, using passerby as the singular noun and passersby as the plural is a clear and consistent choice.
Is Passersby One Word?
Yes. Passersby is normally written as one word.
Correct:
Several passersby witnessed the accident.
Incorrect:
Several passer bys witnessed the accident.
Also incorrect:
Several passer-bys witnessed the accident.
The plural is formed as passersby, with the -s added to passer.
Correct forms
- passerby
- passersby
Common incorrect forms
- passer by
- passerbys
- passer-bys
- passer-bys
- passers-by
The form passers-by can appear in some older or British-style usage, but passersby is the straightforward modern US-English form.
Why Is the Plural Passersby?
The plural form can seem confusing because many English speakers expect to add -s to the end of a noun.
For ordinary nouns, that works:
- book → books
- car → cars
- student → students
However, passerby is a compound noun. The word passer is the noun-like element that refers to the person, while by functions as part of the expression.
Therefore, the plural is formed by changing passer to passers:
passerby → passersby
This pattern is also found in other compound nouns.
For example:
- father-in-law → fathers-in-law
- sister-in-law → sisters-in-law
- runner-up → runners-up
The plural marker is placed on the part of the compound that carries the main noun meaning.
Passerby in a Sentence
Using passerby correctly is easy when you are referring to one individual.
Consider these examples:
A passerby found a phone on the sidewalk.
The phrase a passerby refers to one person.
The passerby gave the phone to a police officer.
Again, the sentence refers to one individual.
One passerby offered to carry the woman’s bags.
The word one also signals that the noun should be singular.
Other examples include:
- A passerby noticed smoke coming from the building.
- One passerby stopped to ask what had happened.
- The passerby quickly called emergency services.
- A passerby gave the lost child some water.
- The injured cyclist was assisted by a passerby.
- A passerby pointed the tourists toward the train station.
- The passerby heard someone calling for help.
- A passerby picked up the dropped papers.
In each case, passerby is singular.
Passersby in a Sentence
Use passersby when the sentence refers to more than one person.
Examples:
Several passersby stopped to watch the street performance.
Because several means more than one, the plural form passersby is required.
More examples:
- Several passersby helped move the damaged vehicle.
- Many passersby ignored the advertisement.
- Two passersby witnessed the collision.
- The loud music attracted passersby.
- A group of passersby gathered outside the store.
- Several passersby stopped when they heard the alarm.
- The performers entertained hundreds of passersby.
- Police spoke with several passersby about the incident.
The plural form works with words such as:
- several
- many
- few
- numerous
- dozens of
- hundreds of
- two
- three
- both
For example:
Many passersby noticed the unusual display.
Passerby vs Passersby With Articles
Articles can help you decide which form to use.
Use a or an with the singular:
a passerby
Use plural forms without a or an:
passersby
Examples:
A passerby called the fire department.
Several passersby called the fire department.
You would not normally say:
a passersby
because a indicates a singular noun.
Likewise, you should not write:
several passerby
because several requires a plural noun.
Common Mistakes With Passerby and Passersby
Because the plural form is unusual, several mistakes are common.
1. Writing “passerbys”
One common mistake is:
Several passerbys stopped.
The correct form is:
Several passersby stopped.
The plural -s belongs after passer, not at the end of the entire word.
2. Writing “passer by” as the noun
Another mistake is:
A passer by helped me.
The standard modern noun form is:
A passerby helped me.
The phrase pass by itself is a verb phrase, but passerby is a noun.
3. Using “passerby” for multiple people
Incorrect:
Several passerby stopped.
Correct:
Several passersby stopped.
The word several indicates that more than one person is involved.
4. Using “passersby” for one person
Incorrect:
A passersby called the police.
Correct:
A passerby called the police.
The article a requires the singular noun.
5. Confusing “passerby” with “pass by”
These words are related but have different grammatical roles.
Pass by is generally a verb phrase:
I pass by the store every morning.
Passerby is a noun:
A passerby saw the accident.
This distinction is important when constructing sentences.
Passerby vs Passersby in American English
For American English, the standard forms are:
Singular: passerby
Plural: passersby
These forms are widely understood and natural in modern US writing.
For example:
A passerby reported the suspicious activity.
And:
Several passersby reported the suspicious activity.
If you are writing an article, news-style content, a blog post, or everyday communication for a US audience, these forms are clear choices.
Is “Passerby” a Noun?
Yes. Passerby is a noun.
It identifies a person who passes by a particular location.
For example:
The passerby stopped to help.
Here, passerby functions as the subject of the sentence.
Another example:
The police questioned a passerby.
Here, passerby functions as the object of the verb questioned.
The plural form works in exactly the same way:
The police questioned several passersby.
Passerby as a Subject
A passerby can appear as the subject of a sentence.
Examples:
A passerby noticed the broken window.
The passerby called for assistance.
One passerby recognized the missing dog.
In each sentence, one person is performing the action.
The plural form works similarly:
Several passersby noticed the broken window.
The passersby called for assistance.
Many passersby recognized the missing dog.
The difference is simply the number of people being discussed.
Passerby as an Object
You can also use passerby as the object of a sentence.
Examples:
The driver thanked a passerby.
The tourist asked a passerby for directions.
The police interviewed a passerby.
For multiple people:
The driver thanked several passersby.
The tourists asked passersby for directions.
The police interviewed several passersby.
This makes the singular/plural distinction especially important in formal writing.
A Simple Trick to Remember Passerby vs Passersby
A useful memory trick is:
One passerby, two or more passersby.
Think about the word passer.
- One passer → passerby
- More than one passer → passersby
Another easy reminder is:
The people are the passers; the location is what they pass by.
So when there is more than one person, the -s goes after passer.
Quick memory rule
1 person = passerby
2+ people = passersby
This simple rule will help you avoid most spelling errors.
Passersby vs Passerby Examples
Here are several side-by-side examples:
Singular:
A passerby helped the elderly man.
Plural:
Several passersby helped the elderly man.
Singular:
One passerby saw the accident.
Plural:
Several passersby saw the accident.
Singular:
The passerby called the police.
Plural:
The passersby called the police.
Singular:
A passerby stopped near the street musician.
Plural:
Dozens of passersby stopped near the street musician.
These examples demonstrate the central rule: passerby is singular, while passersby is plural.
Passerby vs Passersby: Quick Comparison
| Feature | Passerby | Passersby |
|---|---|---|
| Number | Singular | Plural |
| Refers to | One person | Two or more people |
| Standard US spelling | Yes | Yes |
| Example | A passerby stopped. | Several passersby stopped. |
| Common mistake | passer by | passerbys |
If you remember only one thing from this article, remember this table.
When Should You Use Passerby?
Use passerby when you mean one person who happens to be passing a location.
Examples:
- A passerby found my wallet.
- The passerby helped the child.
- One passerby reported the incident.
- I asked a passerby for directions.
The words a, one, and similar singular determiners are strong clues that passerby is correct.
When Should You Use Passersby?
Use passersby when you mean multiple people who are passing a location.
Examples:
- Several passersby stopped.
- Many passersby noticed the event.
- Two passersby called the police.
- The performers attracted dozens of passersby.
Words such as several, many, two, dozens, and hundreds indicate that the plural form is needed.
FAQs
Is passerby singular or plural?
Passerby is singular. It refers to one person who passes by a particular place.
Example:
A passerby helped the injured cyclist.
Is passersby singular or plural?
Passersby is plural. It refers to two or more people who pass by.
Example:
Several passersby stopped to help.
Is “passerbys” correct?
No. The standard plural form is passersby, not passerbys.
The plural -s is added to passer, producing passersby.
Is “passer by” correct?
When referring to a person as a noun, the standard modern form is passerby, written as one word.
Example:
A passerby called the police.
What is the plural of passerby?
The plural of passerby is passersby.
Singular: passerby
Plural: passersby
Which is correct: “a passerby” or “a passersby”?
A passerby is correct because a is used with a singular noun.
Correct:
A passerby stopped to help.
Incorrect:
A passersby stopped to help.
Conclusion
When choosing between passersby vs passerby, the correct word depends on whether you are talking about one person or multiple people.
- Passerby = one person passing by
- Passersby = two or more people passing by
The correct examples are:
A passerby helped the driver.
Several passersby helped the driver.
Do not write passerbys when you mean the plural. The standard plural form is passersby because the plural -s is added to passer rather than to the end of the entire compound.
The easiest rule to remember is:
One person = passerby.
More than one person = passersby.
Once you remember this pattern, choosing between passerby and passersby becomes straightforward.
