pronoun, plural in construction Etymology: Middle English, from Old Norse their, masculine plural demonstrative & personal pronoun; akin to Old English thæt that Date: 13th century 1. those ones, he I,2, people 2, Usage: They used as an indefinite subject (sense 2) is sometimes objected to on the grounds that it does not have an antecedent. Not every pronoun requires an antecedent, however. The indefinite ~ is used in all varieties of contexts and is standard. Usage: They, their, them, themselves: English lacks a common-gender third person singular pronoun that can be used to refer to indefinite pronouns (as everyone, anyone, someone). Writers and speakers have supplied this lack by using the plural pronouns . The plural pronouns have also been put to use as pronouns of indefinite number to refer to singular nouns that stand for many persons . The use of ~, their, them, and themselves as pronouns of indefinite gender and indefinite number is well established in speech and writing, even in literary and formal contexts. This gives you the option of using the plural pronouns where you think ~ sound best, and of using the singular pronouns (as he, she, he or she, and their inflected forms) where you think ~ sound best.
Meaning of THEY in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012