What is the plural of "scenario"?

I am sure they were hypercorrecting: http://www.google.com/search?q=scenario+plur

However they might have been old Italians:

http://fr.wikipedia.org/wiki/Sc%C3%A9nario

Le mot provient de l’italien scenario, « décor de théâtre ». En français, le mot s’est d’abord utilisé sans accent comme en italien, mais cet usage est archaïque.

Ni le pluriel italien archaïque scenarii (ancienne orthographe[1]), ni sa variante francisée scénarii (avec accent aigu) ne sont d'usage courant : le pluriel scénarios est le plus commun en français[2]. Selon l’Académie française, en effet, le mot scénario étant français (en italien, il n'aurait pas d'accent aigu), le pluriel « scénarios » s'impose - exactement comme pour lavabos ou pianos.[3]

The word comes from Italian scenario, “theatre scenery”. In French, the word was originally used without an accent as in Italian, but this is archaic.

Neither the archaic Italian plural scenarii (old spelling[1]), nor its French variant scénarii (with acute accent) is currently used: the plural scénarios is most common in French. Indeed, according to the Académie Française, since scénario is a French word (in Italian, there would be no acute accent), the plural scénarios is required — just as in lavabos, pianos.[3]

A Scenario in Italian is Sceneggiatura according to Wikipedia. Not what we are looking for here according to Francesco

Wiktionary reports that the plural of scenario is scenarios. It also reports that the "hypercorrect" plural of scenario is held to be scenarii (which is nonstandard and rare) since its etymology is Italian.

From scenario, the terminal o having been replaced with an i to form its plural, as per the Italian -o → -i pattern for forming plurals, by analogy with concerti and virtuosi. However, the plural of the Italian word scenario is scenari, making “scenarii” etymologically inconsistent.

According to Merriam-Webster and the OED, the accepted plural of scenario is scenarios. The Corpus of Contemporary American English reports 3683 instances of scenarios being used and none of scenarii.

“scenarios” is the correct one.

And by the way, in Italian the plural is “scenari” (single i).

The correct one is scenaria.

Scenarion is a Greek word, as is the case for almost 1/3 of the english and also Latin languages. It is a direct word loan.

In Greek, the plural of scenarion is 'scenaria', as in plural the endings -on convert into -a. For example, criterion --> criteria. But there are also other similar examples, phenomenon --> phenomena.

Hope this is of some help.

The root of the word Scenario is the word "scene" or "scena" or "scaene" etc. In english language it was imported from italian as stated in previous answers, but it definitely originated from ancient greek.

Look here: http://www.etymonline.com/index.php?term=scene

or here https://en.wiktionary.org/wiki/scene#English

(or same address for the term scaena)

In greek the plural of scenario is scenaria

Similarly to the plural of phenomenon, which is phenomena Similarly to the plural of criterion, which is criteria

At the same time, as more people use this word in english in plural, it may have become common to use it as "scenarios". Perhaps, usage will make it "correct". But if someone wants to keep the trace of the word, the "correct" form is scenaria, despite being in a minority status.

Senario is a greek word. The correct plural is senaria.

Scenario is not from Greek as mentioned above, it's from Italian, and Italian is from Latin.

In Latin, Scenario is from "Scaena", which is then changed one last time to become "Scaenarius", to express something in particular and not the "scene" in general.

The Latin declension of Scaenarius in plural Nominal masculine (yes "scenario" is a masculine word) is Scaenarii.

https://www.online-latin-dictionary.com/latin-dictionary-flexion.php?lemma=SCAENARIUS100

Scenarios became a recurrent mistake because of the common "s" added at the end of a plural word.

Some books use Scenarii as the plural of scenario, and it is a pretty common word in literature.