Chapter 5 of Lindley Murray’s English Grammar (1795) begins thus: A PRONOUN is a word used instead of a noun, to avoid the too frequent repetition of the same word. The definition is useless: ...
The words ‘who’, ‘whom’, ‘which’, ‘whoever’, ‘whomever’, ‘whichever’, and ‘that’ are known as relative pronouns in the English language. A relative pronoun connects a phrase to a noun or pronoun. Thus ...