Indefinite pronouns are those that are not specific, exact or definite. They are also used when the noun is unknown.
Singular: another, anybody, anyone, anything, each, either, enough, everybody, everyone, everything, little, much, neither, nobody, no one, nothing, one, other, somebody, someone, something
Plural: both, few, many, others
Both singular and plural: all, any, more, most, none, some, such