No, I just didn't know about the male and female terminology so I was curious what it was called. Thank you for explaining in detail!The whole thing is an adaptor or a riser mount (depending on the type of rails)
They are part of a rail system
The top is the male end of the rail mount
The bottom is the female end of the rail mount, and features the clamping system
They could be the same type of rail system on top/bottom or they could be different rail systems
Are you asking what it is (as in the female end/clamp) or what type of rail system - eg Weaver/picatinny/dove tail etc