"Titura" - What Does it Mean

The body of the tefillin is made up of three parts: the Bayis, Titura, and Ma'avarta.
The "Bayis - house" is the main body, or square, of the tefillin which "houses" the scrolls carefully placed inside. The "Ma'avarta -passageway" is, as its name clearly indicates, the protruding piece of leather with the hollow inside through which the straps "pass through," and hang, from the tefillin (kind of like a belt loop on a pair of pants - רש"י מנחות לה, א ד"ה מעברתא). The Titura is the bottom square piece of leather which closes the Bayis.
What does it mean?
"Bridge." That's right, the bottom slab of leather acts as a bridge over the gaping hole that the bottomless Bayis leaves. In what language? Aramaic of course.
מנחות לה, א וברש"י ד"ה תיתורא
שו"ע או"ח סי' ל"ב סמ"ד ושו"ע הרב שם סס"ו