Why is there an "r" in "Mrs."?

Answer 1

Well, language changes over time, and “Mrs.” was originally an abbreviation for “mistress.” The pronunciation eventually became “missus,” of course, but the “r” stuck around.

In early modern England, “mistress” was the direct equivalent to “master,” and while the word’s negative connotation eventually crept into the lexicon, it widely meant “a woman who governs; correlative to subject or servant.” The title didn’t even imply a woman was married, nor did its abbreviation—plenty of unmarried women were given the title “Mrs.” in tax lists, parish listings, and other documents of the time.

By the end of the 18th century, speakers had shortened “mistress” to “missus”; the “r” in its abbreviation just never fell away. Around that same time, the term “miss” came to mean an unmarried woman, and it was then that “missus” (and its outdated abbreviation) came to mean a married woman.