A wedding dress or wedding gown is the clothing

Clothing

Clothing refers to any covering for the human body that is worn. The wearing of clothing is exclusively a human characteristic and is a feature of nearly all human societies...

 worn by a bride

Bride

A bride is a woman about to be married or newlywed.The word may come from the Proto-Germanic verb root *brū-, meaning 'to cook, brew, or make a broth' which was the role of the daughter-in-law in primitive families...

 during a wedding

Wedding

A wedding is the ceremony in which two people are united in marriage or a similar institution. Wedding traditions and customs vary greatly between cultures, ethnic groups, religions, countries, and social classes...

 ceremony. Color, style and ceremonial importance of the gown can depend on the religion and culture of the wedding participants.
Weddings performed during and immediately following the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

 were often more than just a union between two people. They could be a union between two families, two businesses or even two countries.