Neapolitan (autonym: ('o n)napulitano [(o n)napuliˈtɑːnə]; Italian: napoletano) is a Romance language of the Italo-Romance group spoken in Naples and most of continental Southern Italy.

[3][4] Largely due to massive Southern Italian migration in the late 19th century and 20th century, there are also a number of Neapolitan speakers in Italian diaspora communities in the United States, Canada, Australia, Brazil, Argentina, Uruguay, Mexico, and Venezuela[citation needed].

Italian and Neapolitan are of variable mutual comprehensibility, depending on affective and linguistic factors.

There are notable grammatical differences, such as Neapolitan having nouns in the neuter form and a unique plural formation, as well as historical phonological developments, which often obscure the cognacy of lexical items.

It may reflect a pre-Latin Oscan substratum, as in the pronunciation of the d sound as an r sound (rhotacism) at the beginning of a word or between two vowels: e.g. doje (feminine) or duje (masculine), meaning "two", is pronounced, and often spelled, as roje/ruje; vedé ("to see") as veré, and often spelled so; also cadé/caré ("to fall") and Madonna/Maronna.

The language had never been standardised, and the word for tree has three different spellings: arbero, arvero and àvaro.

The University of Naples Federico II offers (from 2003) courses in Campanian Dialectology at the faculty of Sociology, whose actual aim is not to teach students to speak the language but to study its history, usage, literature and social role.

There are also ongoing legislative attempts at the national level to have it recognized as an official minority language of Italy.

However, it is also possible (and quite common for some Neapolitans) to speak standard Italian with a "Neapolitan accent"; that is, by pronouncing un-stressed vowels as schwa or by pronouncing the letter s as [ʃ] (like the sh in ship) instead of /s/ (like the s in sea or the ss in pass) when the letter is in initial position followed by a consonant, but not when it is followed by a dental occlusive /t/ or /d/ (at least in the purest form of the language) but by otherwise using only entirely standard words and grammatical forms.

Therefore, while pronunciation presents the strongest barrier to comprehension, the grammar of Neapolitan is what sets it apart from Italian.

In Neapolitan, for example, the gender and number of a word is expressed by a change in the accented vowel because it no longer distinguishes final unstressed /a/, /e/ and /o/ (e.g. luongo [ˈlwoŋɡə], longa [ˈloŋɡə]; Italian lungo, lunga; masc.

Neapolitan has had a significant influence on the intonation of Rioplatense Spanish spoken in Buenos Aires and the surrounding region of Argentina and in the entire country of Uruguay.

The grave accent (à, è, ò) is used to denote open vowels, and the acute accent (é, í, ó, ú) is used to denote closed vowels, with alternative ì and ù.

A couple of notes about consonant doubling: The Neapolitan indefinite articles, corresponding to the English a or an, are presented in the following table: In Neapolitan there are four finite moods: indicative, subjunctive, conditional and imperative, and three non-finite modes: infinitive, gerund and participle.