Ms. or Ms is an English-language honorific used with the last name or full name of a woman, intended as a default form of address for women regardless of marital status. Like Miss and Mrs., the term Ms. has its origins in the female English title once used for all women, Mistress. It originated in the 17th century and was revived into mainstream usage in the 20th century.

Sheila Babs Michaels, also known as Sheila Shiki-y-Michaels, was an American feminist and civil rights activist credited with popularizing Ms. as a default form of address for women regardless of their marital status.