Mrs. originated as a contraction of the honorific Mistress (the feminine of Mister or Master) which was originally applied to both married and unmarried women in the upper class. Writers who used Mrs for unmarried women include Daniel Defoe, Samuel Richardson, Henry Fielding, and Samuel Johnson.
Mrs. is a title used before a married woman’s name (e.g., “Mrs. Carlton”). It shouldn’t be used for an unmarried woman, regardless of her age. It originated as an abbreviation of “Mistress,” but it’s now pronounced [miss -iz] and should be written in its abbreviated form, not as “Mistress.”
Ms. is a general title that does not indicate marital status but is still feminine. Mrs. is a traditional title used for a married woman. Miss is a traditional title used for an unmarried woman. Mx. is a title that indicates neither marital status nor gender.
Mrs. is a title used before a surname or full name of a married female. Mrs. is an abbreviation for the word Missus, it is pronounced like the word Missus. The abbreviation Mrs. has been in use since the sixteenth century, it is a variant of the word mistress.
Mr., Mrs., Ms. and Miss – Full Form and Meaning - GRAMMARIST
The plural of Mrs. is Mmes., a shortening of the French plural Mesdames. English borrowed the French plural for this honorific after adopting Messrs. for the plural of Mr..
The contractions Mr. and Mrs. are short for Mister and Missus/Missis. These contractions, like their longer forms, are used in etiquette to show respect to men and women.
Mr., Mrs., Miss, and Ms.: What They Mean And How To Use Them