I found out in etymology of Mistress that it was considered vulgar to use it for women. I want know why and what is it's exact meaning and origin of word Mister and Mistress.
Both words are variants of master, originally Old French maistre—mistress is the same word with the French feminizing suffix -esse tacked on. A master (or mistress) was anyone who exercised control over subordinate persons—servants. Consequently, Master and Mistress became in the 15th century honorifics bestowed upon men and women who did not have aristocratic titles. The owner of the tavern where Shakespeare‘s Falstaff lodges is Mistress Quickly.
But when mistress came into the English language in the 14th century, it brought along some literary baggage. In the ‘courtly love’ tradition of the 12th century and after it was conventional for the poet to offer his ‘service’ to the woman he loved, he swore to follow and obey her in all things. He therefore referred to her as his ‘mistress’; so the term came to have a secondary meaning of the woman whom one loves, as in Shakespeare’s sonnet: My mistress’ eyes are nothing like the Sun.
Originally the word did not imply a sexual relationship, although it did not exclude it either. But around the year 1600 mistress began to be used as a polite term for a woman with whom a man had a long-term illicit sexual relationship—typically, what the Victorians called a “kept woman”, a woman maintained at her lover’s expense. Over the next two centuries this gradually came to be the primary sense of the word; so by about 1800 it became very awkward to refer to a respectable woman as Mistress Jones or Mistress Smith. What happened was the term shifted its pronunciation when used as an honorific: it became missus and, eventually, mizziz as it is today.