A duchess is a member of nobility who ranks directly below the monarch (excluding immediate family) . The term is the highest of the five noble ranks, which include duke, marquess, earl, viscount, and baron. A duchess is the wife or widow of a duke, or a woman who equally holds the rank of duke in her own right. While both duchesses and princesses are royalty, and princesses technically outrank duchesses, the relationship between the two titles is not always clearly defined. Princesses are usually the daughters or granddaughters of a king or queen, and a "commoner" can gain the title of princess by marrying a prince, with the possibility of later becoming a queen. A princess or queen can also have the title of duchess and vice versa. For example, when Sarah Ferguson married Prince Andrew, she became a princess, and because Andrew also held the title of Duke of York, she became the Duchess of York. In summary, a duchess is a noble title that is held by the wife or widow of a duke, or a woman who equally holds the rank of duke in her own right.