An indefinite pronoun is a pronoun that does not refer to a specific person or thing.
In English, there are singular indefinite pronouns, plural indefinite and both singular and plural indefinite pronouns.
Singular Indefinite Pronouns
Another, anything, everybody, neither, one
Anybody, each, everyone, nobody, somebody
Anymore, either, everything, no one, someone.
An indefinite pronoun must agree with its verbs and in number with its possessive pronoun.
The above indefinite pronouns are used with singular verbs.
They are also used with singular possessive pronouns.
Examples: Agreement with verbs
Correct: Everyone has heard of Lake Turkana.
Incorrect: Everyone have heard of Lake Turkana.
Correct: Nobody knows what happened to Samuel Wanjiru.
Incorrect: Nobody know what happened to Samuel Wanjiru.
Correct: Everything about the old man remains a mystery.
Incorrect: Everything about the old man remain a mystery.
Agreement in number with possessive pronouns
Correct: Neither believed his/her eyes.
Incorrect: Neither believed their eyes.
Correct: Each strained his/her neck to see.
Incorrect: Each strained their neck to see.
Plural indefinite pronouns
Both many few several
These indefinite pronouns use plural verbs and possessive pronouns.
Examples: Plural verbs
Correct: Few know about Lake Olbolsat.
Incorrect: Few knows about Lake Obolsat.
Correct: Both stand by what they believe.
Incorrect: Both stands by what they believe.