relative pronoun

word that introduces subordinate clauses or noun clauses (Grammar)

A relative pronoun is a pronoun that marks a relative clause within a larger sentence.A relative pronoun links two clauses into a single complex clause. To this extent, it is similar in function to a subordinating conjunction. Unlike a conjunction, however, a relative pronoun stands in place of a noun. Compare:(1) This is a house. Jack built this house.(2) This is the house that Jack built.
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Noun
1. a pronoun (as `that' or `which' or `who') that introduces a relative clause referring to some antecedent
(hypernym) pronoun