Indefinite pronouns are words that refer to a person, place, or thing that is not specifically named. Examples include:
* Singular: everyone, someone, anyone, nobody, each, either, neither, one
* Plural: both, few, several, many
Antecedents are the nouns or pronouns that indefinite pronouns refer to.
The Rule:
If an indefinite pronoun is singular, its antecedent should also be singular.
If an indefinite pronoun is plural, its antecedent should also be plural.
Examples:
Correct:
* Everyone brought their own lunch. (Everyone is singular, and "their" refers to everyone)
* Both of the students finished their assignments. (Both is plural, and "their" refers to both students)
Incorrect:
* Everyone brought his own lunch. (Everyone is singular, but "his" is singular and doesn't agree)
* Both of the students finished his assignment. (Both is plural, but "his" is singular and doesn't agree)
Note:
* The indefinite pronoun "none" can be either singular or plural. It should agree with its antecedent.
* None of the students were late. (None is plural because "students" is plural)
* None of the work was finished on time. (None is singular because "work" is singular)
* The indefinite pronoun "any" can be singular or plural depending on the context.
* Any of the students can attend. (Any is plural because "students" is plural)
* Any student can attend. (Any is singular because "student" is singular)
In formal writing, it's generally best to avoid using singular indefinite pronouns with plural antecedents. Instead, rewrite the sentence to avoid the ambiguity. For example, instead of saying "Everyone brought his or her own lunch," you could say "All of the students brought their own lunch."