I looked this one up, wanting to use it in a book set in 1917…only to find a history I knew nothing about!
So mannequin has been around since 1902, but it wasn’t a form used to display clothes. Or rather, not a non-living one. When mannequin first appeared, it was the term used for a fashion model! So those well-formed young ladies who modelled clothes were the mannequins, not the dress-forms used in display windows. That meaning didn’t come along until 1939!
That said, the word did sometimes mean “artificial man” before 1902, apparently especially in the translation of Hugo. This because it’s directly from French.
Interesting to note that we also have the word manikin, from the Dutch for “little man,” which was specifically a jointed figure used by artists. So the little 4-inch tall artist’s model I got my daughter for Christmas is a manikin. The meanings have blended over the years, but they were once two distinct things from two different languages. Who knew?
Interesting! I guess you'll have to stick with dress form.