relative pronoun

Pronoun that links an adjective clause to a noun or pronoun in the main clause.

‘That is the lady who owns the famous dog.’ ‘You are the girl whom I sent from the room last lesson.’ ‘We saw the car that caused the accident.’ ‘I found the tunnel through which he escaped.’ Each italicized unit is a subordinate adjective clause (see subordinate clause). Each initial word relates the clause to a noun in the main clause. That is its ‘relative’ function (acting as a conjunction).

Unlike conjunctions, however, the words who, whom, that, and which have a noun function in their clauses. Who is the subject of its clause, whom is the object, that is the subject, and which is governed by the preposition ‘through’. The words have both a relating and a noun function; hence the term ‘relative pronoun’.