Gown

A gown, from the Saxon word, "gunna", is a usually loose outer garment from knee- to full-length worn by men and women in Europe from the Early Middle Ages to the 17th century, and continuing today in certain professions; later, "gown" was applied to any full-length woman's garment consisting of a bodice and attached skirt. A long, loosely fitted gown called a Banyan was worn by men in the 18th century as an informal coat.
The gowns worn today by academics, judges, and some clergy derive directly from the everyday garments worn by their medieval predecessors, formalized into a uniform in the course of the 16th and 17th centuries.
About.
A modern gown refers to several types of garments. It can refer to a woman's dress, especially a formal, or especially fancy dress. It may also refer to a nightgown or a dressing gown. In academia, gowns are also worn for various occasions. 
History.
The "gunna" was worn by Anglo Saxon women and consisted of a long, loose outer garment. The "gunna" was also called a cote, surcoat or a robe.
Gowns were worn by students attending early European universities in the 12th and 13th centuries. The gowns and hoods worn would indicate their status. From the 14th to the 17th centuries, the term gown was used to describe any long, loose, robe-like garment worn by both men and women.
In 1500s Italy, gowns were also known as "camora" or by regional names in various locations. The look of the "camora" changed over time, starting out with a high waist and low neckline at the beginning of the century and gradually becoming low-waisted and high-necked by the end. Italian women also wore an overgown called a "vestito" or a "roba". In turn, these might be covered by a "robone" which was lined with fabrics or furs for warmth.
By the late sixteenth century, gowns were no longer in style in Italy except where they were worn to denote a professional station, such as a banker or priest. 
In the 17th century, women's gowns in the American colonies included trimming around the neck and down the bodice, or in the case of an open gown, down front edges from hem to neck. Gowns may also have borders of silk, ribbons and other decorations. Women in the American colonies wore short gowns as working clothing and informal clothing during the 18th century. The gowns were t-shaped and had side godets for additional volume.