Miss, Mrs and Ms have a common ancestor: they are all versions of the word mistress (from Old French maistresse, the feminine of maistre). Mistress was used to address all women, but it evolved into two forms designating a woman’s marital status: Mrs for a married woman; Miss for an unmarried one.
A further variation in parts of America was Miz for women, married and unmarried, both in fiction (Miz Scarlett in Gone With the Wind) and in fact (during the 1970s President Jimmy Carter’s mother was universally known as Miz Lillian). Meanwhile, mistress had acquired the meaning of a woman who has an ongoing extramarital sexual relationship with a man. By the late 1940s some women were beginning to agitate for a prefix that didn’t identify their marital status.As early as 1949 there had been occasional low-profile mention of Ms as a possible nondiscriminatory courtesy prefix for all women, but it did not have a smooth passage into everyday language.
The American Business Writing Association and also the National Office Management Association had viewed the term with favour, but the general public ignored it. A turning point came in 1961. Sheila Michaels was a member of CORE (Congress of Racial Equality), and like other feminists was seeking an honorific that didn’t disclose her private status. One day a newspaper dropped into her letterbox and she noticed what seemed to be a misprint in the address: Ms. She had never seen it before, but decided that this was what she sought. There was still difficulty promoting the idea, but in a later radio interview discussing feminism, Michaels suggested that Ms be adopted, and pronounced as she had heard Miz in her home state of Missouri. A friend of Gloria Steinem’s heard the interview, and in 1971 suggested it to Ms Steinem as the name for a new magazine about to be launched. The first issue of Ms. Magazine sold 300,000 copies in one week, and the ‘new’ honorific started to take hold. But there were still some roadblocks: the New York Times initially held out and would not publish the new word, in 1984 dismissing Ms. as ‘business-letter coinage too contrived for news writing’. But in 1986 it finally succumbed.