The noun 'passerby' is the singular form. The plural form is passersby.
The possessive form of the singular noun passerby is passerby's.example: That's a passerby's dog barking.
Passerby
The singular form is passerby; the plural for is passersby.
The plural form for the compound noun passer-by is passers-by.
Passer-by.
The plural form of "passerby" is "passersby."
The possessive form for the noun passerby is passerby's.
The singular form of the demonstrative pronoun 'these' is this.
The singular form of feet is foot.
The singular form of "hypothysis" is "hypothesis."
The singular form is ombudsman.
The singular form is hilum.