Onlooker vs. Passerby — What's the Difference?

One that looks on; a spectator or bystander.

A person who passes by, especially casually or by chance.

A spectator; someone looks on or watches, without becoming involved or participating.

Alternative spelling of passer-by

Someone who looks on

One who passes by, especially casually or by chance; one not directly involved in some action; a passer.

A person who passes by casually or by chance