The term prime minister in the sense that we know it originated in the 18th century in the United Kingdom when members of parliament disparagingly used the title in reference to Sir Robert Walpole. Over time, the title became honorific and remains so in the 21st century.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What came into use in the 1800's?
unanswerable