relative clause
- a subordinate clause introduced by a relative pronoun, adjective, or adverb, either expressed or deleted, especially such a clause modifying an antecedent, as who saw you in He's the man who saw you or (that) I wrote in Here's the letter (that) I wrote.
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018