A couple of months ago, an Italian friend brought to my attention a quirk of Italian usage. Like English, Italian has adopted the Latin word forum to mean "a place for public discussion". In English, as usual with borrowed Latin words, the plural is sometimes "fora" (the original Latin plural) and sometimes "forums" (the regular English form). In Italian, borrowed words are often treated as invariabile ("invariant"), so that the plural is the same as the singular. For forum this yields the plural "forum", and (for example) "in tutti i forum" (meaning "in all forums") is common on the web.
But there are also two Italian words foro, plural "fori": one means "hole, opening", and the other means "court, tribunal".
The Italian noun foro "hole" and verb forare "pierce, prick, punch, puncture, drill" are apparently related to the (rare) Latin verb foro "bore, pierce", cognate with English bore. (The same root also shows up in foramen "opening or aperture", familiar from its many reflexes in Latin anatomical names.) Italian foro "court, tribunal" presumably derives from Latin forum, the forum being a place where (among other things) justice was dispensed. (The etymology of Latin forum is apparently unknown.)
The issue then is what to call the various regional and global talking-shops such as those run by the United Nations. In English, they're "multilateral forums". In Italian, they might be treated as "forums", in which case the phrase should probably be "i forum multilaterali" — or as "tribunals", in which case the phrase should be "i fori multilaterali". But if you expect them to be "forums", and don't think of them at all as law-courts, then the phrase "i fori multilaterali" apparently evokes a different set of ideas, and often a few chuckles.
There are certainly examples of "forum multilaterali" out there. Thus this 2006 document from the Italian chamber of deputies explains that
L’Unione europea è attiva a livello internazionale, in tutti i forum multilaterali per l’abolizione della pena di morte.
In English, this would be something like
The European Union is active internationally in all multilateral forums for the abolition of the death penalty.
Sul piano della politica internazionale, il Ghana continua a svolgere un ruolo molto attivo in tutti i fori multilaterali, a cominciare dalle Nazioni Unite, alle cui forze di pace partecipa in modo significativo, soprattutto nei Paesi africani.
The English version of the same page renders that sentence this way:
In terms of international politics, Ghana continues to play an active role in all multilateral forums. Its forces are actively involved in United Nations peacekeeping activities in a significant way, especially in African countries.
And a few months ago, according to the Corriere della Sera, ("Giappone, l'Imperatore: anche io al buio: Lettera di Napolitano: 'Il popolo ce la farà'", 3/14/2011):
All'imperatore Akihito ha scritto il presidente Giorgio Napolitano, [...] «Da oltre sessant'anni – si legge nella missiva inviata da Napolitano – i nostri Paesi collaborano insieme in tutti i fori multilaterali nel sostenere la sicurezza e nel promuovere lo sviluppo economico mondiale.
President Giorgio Napolitano has written to the Emperor Akihito, [...]
"For over sixty years – reads the letter sent by Napolitano – our two countries have worked together in all multilateral forums to support security and to promote world economic development."
[My knowledge of Italian is based largely on triangulation from Latin and French, so I apologize in advance for mistakes and misapprehensions.]