Titulum is correct. You could call it a chicane if you want a word more people know.
https://gwern.net/doc/history/2007-keeley.pdf
End of page 62 and all of 63 - looks like a "screened" baffled gate.
"Titulum" is the name of that specific wall.
I found a Wikipedia article that expands on motivations for the design: Titulus_(fortification)
The description in the wiki article and the orientation of the diagrams on page 63 of the Keeley document convince me that the ~~more common arrangement was to place the detatched screening wall segment on the exterior of the curtain with an~~ interior version sometimes used either instead of or in addition to the exterior screen.
Edit: I think I read the pg63 diagram orientations wrong, so I think my point is mostly that it can be either inside or outside, and that this whole PDF is really cool.
My friends and I all just call that a wall
The initial defensive entrance of a castle was called a barbican, I'm not sure if that wall you're describing would be considered as part of the barbican or maybe it has its own specific name. It's like a chicane almost
I don't think I've ever seen this in a fort. Usually they would extend the wall outward and place a barbican (a fortified external gatehouse) in front of the regular gate.
I don't know, and I spent way too long trying to figure it out.
Tip Of My Tongue
Crowdsource your search for the name of that thing.
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