Passersby or Passerbys – Which is Correct?

If you fall and hurt yourself on the sidewalk and no one helps you, should you be angry at the passerbys or passersby who ignored your plight?

Based on the way most English nouns become plural, we might think that passerbys would be the correct answer. However, passersby occurs in print sources far more often than passerbys. How can this be?

The difference between these words comes down to internal pluralization—a way to pluralize phrases and compounds where the noun is not the final word in the construction.

What is the Difference Between Passersby and Passerbys?

In this article, I will compare passersby vs. passerbys. I will outline the correct spelling and use it in a few example sentences to show its proper context.

Plus, at the end, I will show you a helpful memory tool that you can use as a reminder of whether to use passerbys or passersby for your own writing.

When to Use Passersby

definition of passersby definition of passerbysWhat does passersby mean? Passersby is a plural noun. It is the plural form of passerby, which is someone moving alongside a person or event.

The verb to pass means to move alongside, and the noun passer refers to someone who does so. Its plural is passers. By can be a synonym of alongside in some context, as in the phrases slide by or walk on by. Thus, passersby refers to people who pass by.

These sentences use passersby in its proper context,

  • Passersby were alarmed when Ellie fell into a manhole while crossing the street.
  • None of the passersby stopped to help a man who had been beaten on the sidewalk in broad daylight.
  • Dozens of pint-sized zombies descended on downtown Washington on Wednesday afternoon, drawing a crowd of smiling passersby with their Halloween-appropriate rendition of Michael Jackson’s “Thriller.” –The Washington Post

The singular form of passersby is passerby. Passers is the part of the compound that is plural, so it is also the part that drops the -s to become singular.

When to Use Passerbys

What does passerbys mean? Passerbys is an incorrect pluralization of passerby and should be avoided.

passersby versus passerbys

The above chart graphs passerbys vs. passersby over time, and, as you can see, passersby is clearly the only accepted spelling. Bryan Garner, in his book Garner’s Modern English Usage, estimates the gap between the two to be 199:1. In other words, never use passerbys.

The confusion arises from the general rules of English pluralization. Most singular words become plural when an -s is added to the end of the word. Thus, it would be intuitive for passerby to become passerbys, according to the same rules.

As I noted above, however, passersby is an exception to this general rule. Passer is the part of the compound that becomes plural, not by. Thus, that is the part of the word that receives the -s. This formation is called internal pluralization, and it is common in phrases where the noun is not the final word, like sons in law and runners up.

If you wanted to describe something that belonged to some passersby, you would use the possessive passersby’s.

Trick to Remember the Difference

  • what is the plural form of passerbyPassersby is the only accepted spelling of this word.
  • Passerbys is a spelling error.

Since passer is the word that becomes plural, and its plural is passers, you should always be able to remember that passersby is the correct version of this word.


Is it passersby or passerbys? Passersby refers to people who move alongside something, in other words, bystanders who aren’t actually standing still.

  • Passersby is the correct spelling.
  • Passerbys is a common mistake.