What does "Pilegesh" Mean?

For those who frequent the pages of Gemara or any halachic work, you may have encountered the word "פלגש," commonly translated as "concubine." Where does this word come from?
Many are of the impression that it is a combination of the Aramaic word "פלג - half" and the Hebrew word "אשה - woman/wife." The simple connotation is that such a woman is not a "full" wife, but only "half" a wife (for various reasons: either because she does not receive a kesubah or because she is not intended for procreation, see references.)
In a similar vein, albeit slightly different, the Malbim explains that the word is really "פלג" half, and the extra "ש" is a common linguistic phenomenon where an extra letter is added at the end of the word (like "ערפל" from "ערף" or "שקערורות" from "שקע," etc.)
שפתי חכמים לרש"י בראשית כה, ו אות ר
מלבי"ם "התורה והמצוה" לספרא אות פט
ועי' חומש "תורה מאירה" (לר' מאיר מאירי) בראשית כב, כד בשם ר' וואלף הידנהימר
ועי' שאלת יעב"ץ ח"ב ריש סי' ט"ו
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"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