
Confusion is increasing eheheh
OK, let's make it simple comparing "dos & donts" with the italian word for tomato/tomatoes:
"
pomodoro/pomodori"
the etimology of this word is a composite of:
"pomo" (pome/apple)
+
"d'oro" (golden)
Nowadays it has definitely prevailed the plural form "pom
odor
i", which is more
practically applied to the singular "pomodor
o" (just as everything else, let's say "gatto"->"gatti", "pandoro"->"pandori"), not considering the plural of the detached main word "pomo" (pomi) but simply the plural of a whole word like others.
Some time ago it was quite predominant to say the plural as "pom
idoro", following a
logical sense, as if it was still the detached components "pom
i d'oro" (pomo -> pomi), but it was quite difficult to get it as a plural word, that's
why "pomodori" prevailed.
So, following and learning from this "historical" path of such word I would rather consider "(two) donts" as a practical plural for the word "(a) dont" (derived from "don't")... but the us/uk english speakers followed evidently a different logic
Now that I had better searches I found out that it is commonly written as:
"
do's and don'ts"
(
1.770.000!! results against the 406.000 of this topic's title)
So I guess this is the "correct" form.
PS: Just if you were wondering... I posted the "pomodori" thing just to
report a clear -I hope- explanation of why we adopted one form instead of another one 