Boning

Boning is most commonly used in corsets today and in older dresses. it is designed to stop the fabric wrinkling because it is pulled so tight to the body. In the 16th and 17th century, boning was used to force the body to conform to the desired cone shape with the use of wood even being used. Nowadays it is considerably more relaxed but keeps the same idea.

Lolita Troubadour

I found this image on a website but as a modern day example of a use of boning we can see the vertical lines create the cone shape at the waste.

This particular corset is exhibited in the V&A museum of fashion in London. It is defined as "The shape of the 18th and 19th century fashion". The lines and therefor shape have been created using the boning technique