If you think about honorifics, it makes sense why “Miss” turns into “Ms.” and “Mister into “Mr.,” but why does the word “Missus” suddenly turn into “Mrs.”? Where on earth does that extra “r” come from?
One writer from Mental Floss had the same question, so she did a little digging to find out more about the discrepancy.
Turns out, the abbreviation “Mrs.” was originally short for “mistress,” she found out, and the word had a more general meaning of a woman who is in charge of something, such as a household. Overtime, the pronunciation of the word changed from “mistress” to “missus,” and eventually the “r” was dropped. By the 18th century, “miss-iz” was the correct way to say the word, and “mistress” was gone altogether.
Although eventually “missus” became the word everyone used verbally, the written version remained “Mrs.,” as it was regarded as more formal. The term stuck, and here we are today with an abbreviation that doesn’t quite match its pronunciation.