Women were property
If men owned women, as feminists claim, then men were keeping women as chattel slaves, by definition. The ability to be able to buy and sell an item is a necessary condition to establish ownership but it alone is not sufficient.
In many societies people could sell their children so an argument could be made that children *were* property.
The feminist historical narrative is so pervasive that even many nanti-feminists buy in to it.
Wife selling If you can't buy and sell something you don't own it.
Many people confuse Coverture with ownership.
Many slave owning societies (including the antebellum South in the US) had limits on how slaves could be treated but this did not stop it being slavery. Sometimes humans have limits on their rights for other ownership (eg heritage listed property) but they still own it.