Passersby-Passerbys | Commonly Confused Words

Passersby

/ˈpɑːsəzˈbaɪ /

People who are walking past a particular place, often without stopping

People who are walking past a particular place, often seen or encountered by chance

Passersby is the correct plural form of passerby.
Remember that in English, some compound nouns pluralize the first element, making passerby into passersby.
Much like attorneys general, it's the adjective that gets a plural form, not the noun.
Passerbys is incorrect because it attempts to pluralize the noun instead of the adjective.
Imagine youre referring to multiple people walking by; hence, passers go by'.