If unsure, use s or es!

I’ve seen some pretty bad abuses of the English language before…including the depressingly common affectation “virii” when referring to multiple viruses.
Some people guilty of this affectation will defend it to the bitter end, claiming that that’s the proper Latin pluralisation, and citing other English examples. This topic has been debated elsewhere plenty of times, so in short.

1. Viruses is the plural of virus.
2. Virii is not a word in any language, past or present.
3. The Latin word for Virus did not have a separate plural form.
4. The English plural of Cactus is Cactuses (look it up), with Cacti being an acceptable alternative (note the single i)
5. The English plural of Octopus is Octopuses, with Octopi being an acceptable alternative. (Again, note the single i).
6. Viri is not an acceptable plural of Virus either

So having got that out of the way – the newest and most ridiculous (that’s ridiculous with an i, not an e) bastardisation of our language just showed its ugly face in a comment on Slashdot – “Scenarii” – apparently as a plural form of scenario. I have no idea what went through the mind of the author prior to posting it, but I can’t figure out why anyone would decide that replacing a final syllable with a double i would make an acceptable plural…almost every English word is pluralised by adding s, or es to the end. Even those that that aren’t pluralised that way eventually end up adopting that form as acceptable (like the abovementioned cactuses and octopuses) .

So to summarise – if you are ever unsure how to pluralise an English word, just add -s if the word ends in a non s sound, and -es if it already ends in an s.

If you follow that rule, you might be wrong occasionally, but if anyone even notices, they’re likely to either assume it was just a typo, or politely correct you, understanding how easy it is to make a simple mistake like that.
If however, when confronted with a confusing multiplicity that you just have to form a word for, you think – “I know, I’ll just drop the last syllable and add an i, because that’s how they do it in Latin, so it’ll make me look real smart. Or maybe I’ll add two, and then I’ll look twice as smart!” – then you are doomed to make yourself actually look twice as stupid instead. Rather than politely correct you, people are likely to look at you as if you’re some kind of moron who can’t even find the “s” key on their keyboard.
So repeat after me – “when unsure, add -s or -es!”