A relative pronoun is a pronoun that marks a relative clause within a larger sentence. It is called a relative pronoun because it relates to the word that it modifiers.
A relative pronoun links two clauses into single complex clause. To this extent, it is similar in function to a subordinating conjunction. Unlike a conjunction, however, a relative pronoun stands in places of a noun.
Compare:
(1) This is a house. Jack built this house.
(2) This is the house that Jack built.
Sentence (2) consists of two clauses, a main clause (This is the house) and a relative clause (that Jace built). The work that is a relative pronoun. Within the relative clause, the relative pronoun stands for the noun phrase it references in the main clause (its antecedent), which is one of the arguments of the verb in the relative clause. In the example, the argument is the house, the direct object of built.
Other arguments can be relativised using relative pronouns:
Subject: Hunter is the boy who kissed Monique.
Indirect object: Hunter is the boy to whom Monique gave a gift.
Adpositional complement: Jack built the house in which I now live.
Possessor: Jack is the boy whose friend buit my house.
Not all languages have relative pronouns. Those that to tend to use words which originally had other functions; for example, the English which is also an interrogative word. This suggests that relative pronouns might be a fairly late development in many languages.
In English, different pronouns are sometimes used if the antecedent is a human being, as opposed to a nonhuman or an inanimate object (as in who/that). In some languages, the relative pronoun is an invariable word.
(5) This is a bank. This bank accepted my identification.
(6) She is a bank teller. She helped us open an account.
With the relative pronouns, sentences (5) and (6) would read like this:
(7) This is the bank that accepted my identification.
(8) She is the bank teller who helped us open an account.
In sentences (7) and (8), the words that and who are the relative pronouns. The word that is used because the bank is a thing; the word who is used because she is a person.
Relative pronouns:
| Time | Reason | Person | Place | Thing | |
|---|---|---|---|---|---|
| Subject | - | - | Who, That | Where | That, Which |
| Object | When | Why | Who, Whom, That | - | That, Which |
| Possessive | Whose | - | Whose | - | Whose |