[Ancapistani]

Huh, that’s a new one to me.

I found a couple of usages in academic publications, but they don’t give me any more context as to meaning. That leads me to believe that it’s not a legal term.

I can’t find any meaning other than the “sound a horse makes” in any dictionary, either.

ETA: Apparently, the old English “nēah” meant “near”. That seems to be the the root of the work “neighbor”.

Interestingly, it looks like “neigh” (like a horse) and “neighbor” both came into use in English in the 12th Century. Perhaps coincidental.