A relative pronoun, used esp. in referring to an antecedent noun or clause, but sometimes with reference to what is specified or implied in a sentence, or to a following noun or clause (generally involving a reference, however, to something which has preceded). It is used in all numbers and genders, and was formerly used of persons. [1913 Webster
"And when thou fail'st -- as God forbid the hour! --
Must Edward fall, which peril heaven forfend!"
"God . . . rested on the seventh day from all his work which he had made."
"Our Father, which art in heaven."
"The temple of God is holy, which temple ye are."