[int_19h]

We don't know what Herbert actually meant by "Bene Gesserit", or even whether it has strictly one meaning, since he never elaborated on that. Given how syncretic everything else is, it is entirely plausible that there are multiple references encoded in the name. The Latin one is fairly obvious given that they refer to each other as "Reverend Mothers".

But then note that Bene Tleilaxu is clearly not Latin, and makes more sense if you interpret the word "bene" ("bani") in its Arabic meaning - "descendants of", in practice often referring to tribes and similar groupings (as in Bani Quraish or Bani Isra'il) - Tleilax being their home planet. If we apply the same to "Bene Gesserit", it would mean "Daughters of ???". One possibility then would be Arabic "Jazirah", "peninsula".

An even more interesting theory along these lines is that "Gesserit" refers to the mythical demon-slaying hero-king Gesser (aka Geser aka Gesar) of the Mongolian and Tibetan folklore. In Mongolian, "... of Gesar" is "Geseriyn". Gesar is the Chosen Son of the Sky God (head of the pantheon), the first man who descended from Heaven to purge the world of evil demons that menace humanity - it sure does make for some interesting parallels with Kwizats Haderach...

Again, to re-iterate, it's entirely possible that all of these are simultaneously true. Herbert liked referencing obscure (to his culture) folklore, so a play on words like this could well be intentional.