Definition: The term glycerin soap is really a misnomer.
All real soap is glycerin soap. I repeat, all real soap (not made with synthetic detergents) is essentially glycerin soap.
Glycerin is a byproduct of the soap making process.
Oils + lye (with some water) = soap + glycerin
What many people call glycerin soap is actually transparent soap. Transparent soap is real soap too...it just goes through a hot process where sugar and alcohol are added as "solvents" to keep the soap crystals from becoming opaque.
Without this crystallization, the soap remains clear. You could take any of your soap recipes and adjust the process to make them transparent. (Naturally, some recipes will work better than others, but that's basically the case.)
Also Known As: Some people also refer to "melt and pour" soap as glycerin soap. This is, as well, true. But there are clear and opaque melt and pour soaps.
Alternate Spellings: I've seen it spelled glycerin and glycerine.
Examples: Try my glycerin soap. It's all natural and super moisturizing.
Oh, we don't use melt and pour soap, our soap is a glycerin soap.
Our homemade soap retains all its natural glycerin.