Foreign plurals => English singulars

     [This is a fast-access FAQ excerpt.]
Some uses of classical plurals as singulars in English are
undisputed:  "opera", "stamina", "aspidistra".  ("Opera", still used
as the plural of "opus", became singular in Vulgar Latin, and then
in Italian acquired the sense "musical drama", giving rise to the
English word.)  "Agenda" once excited controversy but is now
accepted.  Others are the subject of current controversy:  "data"
(used by Winston Churchill!), "erotica", "insignia", "media",
"regalia", "trivia".  Yet others are still widely stigmatized:
"bacteria", "candelabra", "criteria", "curricula", "memorabilia",
"phenomena", "strata".
   "Bona fides", "kudos", and "minutia" are singulars in Latin or
Greek.
   "Graffiti" (plural in Italian) is disputed in English.  But
"zucchini" (also plural in Italian) is the invariable singular form
in English (the English plural is "zucchini" or "zucchinis").
"Biscotti" seems to be going the same way.  The names of types of
pasta (cannelloni, cappelletti, ditali, fusilli, gnocchi,
maccheroni, manicotti, ravioli, rigatoni, spaghetti, spaghettini,
taglierini, tortellini, vermicelli, ziti, which are masculine plural
in Italian; and conchiglie, farfalle, fettuccine, linguine, rotelle,
which are feminine plural; some of the -e words are often spelled
with -i in English; maccheroni is "macaroni" in English) are
treated as mass nouns in English:  they take singular verbs, but
plurals are not made from them.  (Many of the words listed as
disputed above are also treated as mass nouns when they are used as
singulars.)