These above five words are ones I'd heard, but I just didn't really know the difference. Here's a brief rundown.
Corset - I think we all have a preconceived notion of this one: undergarment that is uncomfortable, confining, and makes you hold your posture; however, if made well, it shouldn't be this way. It should smooth out your torso and provide the fashionable shape of the period. Elizabeth Stewart Clark mentions that in period sources, a stay is the same thing. In modern living history, however, "we often use the term 'corset' to describe a steel-boned, fashion-shaping undergarment, and the term 'stays' to describe a more gently-fitted undergarment with shaping provided from a few bones, or cording and quilting" (The Dressmaker's Guide, 117).
The Workwoman's Guide (1840) gives directions on how to make one starting on page 81 & Plate 11, Figure 22.
The Dressmaker's Guide page 117.
While reading through The Workwoman's Guide, I ran into the word "shift" on page 46. The corresponding figures found on Plate 6 looked something like a baggy shirt-dress. Liz Clark refers to this as a chemise. A shift/chemise is basically a slip (modern term) worn next to the skin and under the corset. The Workwoman's Guide teaches how to make a few variations, Liz has an entire chapter on them in The Dressmaker's Guide (chapter 4) as well as a FREE Chemise Pattern.
chemisette the same? No. I e-mailed Liz to clarify this one for me. Here's what she said:
A chemisette is a little different; it's a white accessory piece that can either be shaped like a modern "dickie" or is sometimes a complete white underbodice, sleeves included. Either way, a chemisette is made of very fine, sometimes sheer white cotton or linen. The chemisette is worn to fill in the neckline of a low-bodiced or half-high bodiced dress for daywear. Full underbody styles also fill in a short or open dress sleeve. Chemisettes can be extremely decorative, with tucks, insertions of lace or white embroidery, braidwork, complex embroidery patterns (usually white thread on the fine white cloth.)