A shirt dress is a woman's dress that will take certain aspects of men's shirts and incorporate them into the dress itself. Examples of parts of men's shirts that are commonly incoporated into the shirtdress include collars, buttons down the front, cuffed sleeves and the material used such as cotton or silk which is a common material for men's dress shirts.
As they are typically cut without a seam at the waist, these dresses often have a looser fit, usually relying on a belt to define the waist.
One of the biggest benefits of the shirtdress is that it can be worn for many different occasions depending on what else it is worn with. For example: for an evening look, you can forego stockings and keep your legs nude, add in some thin strappy high heels. Throw in a sophisticated pearl necklace and you have a very sexy yet sophisticated look to go out on the town.
In short, the shirtdress fits all occasions but can be mixed and matched with other parts of your wardrobe for just about any occasion. If you wear it with jeans, the look is totally different than if you wore it with sheer stockings. Another good idea is to wear a sleeveless sweater knit shirtdress over a thin long-sleeve T short or blouse. By combining shirtdress with other layers, you have added interest.