Structurally, Sicilian is a distinct Romance language. Like Italian, it descends directly from Vulgar Latin and did not originate as a variety of Italian. Sicilian has a vowel system distinct from Italian, its own morphology and a lexicon layered with Greek, Arabic, Norman French, Catalan and Spanish borrowings.
Sometimes people argue about this because dialetto and "dialect" are not equivalent in the way they are used when they describe the relationship with the standard language.
I am a teacher from Catania, Sicily, raised in a family that mainly spoke Italian rather than Sicilian, but I was exposed to it through the local environment.
Why is it confusing
If in Italian dialetto covers regional languages that did not become the national standard, in English "dialect" implies a variety of a bigger language. Both Sicilian and Italian descend from Latin, and standard Italian comes from Tuscan. Sicilian, instead, developed along its own trajectory in Sicily.
In everyday Italian, dialetto primario refers to traditional local speech varieties such as Sicilian or Neapolitan, so Sicilian, despite being a distinct Romance language, is referred to as a "dialetto" in Italian. In English "dialect" generally means a variety of the standard language, distinguished by its own characteristics. Cockney, for example, is a variety of English, because it includes more than just a peculiar way of pronouncing words.
Proper Scots is maybe the closest English-language parallel to Sicilian: a sibling of English descended from Old English.
What we speak in Catania, with its intonation, is the equivalent of Cockney, a variety of Italian, while Sicilian is not. It's the italiano regionale. Sicilians often use words or ways of saying that are connected to the geographic area, and the intonation easily reveals where the speaker is from. Italiano regionale is a dialetto secondario, in which the influence of the local dialects on Italian is clear.
In Sicily, 61.5% still report using dialetto at home, exclusively or alternating with Italian. Often, in the same conversation, both Italian and Sicilian are used in rotation, sometimes in a single sentence.
A dialetto in the Italian sense is a sibling of Italian, not a subset of it. So the Italian word carries a hierarchy that the English word does not: language and dialetto are opposed.
Certainly Italian had a later influence on Sicilian through media, bilingualism and education, but influence is not the same as descent.
What Sicilian actually is
Sicilian is a group of varieties: Catanese is different from Palermitano and Messinese. Underneath everything is Latin. For example, Sicilian inherited the verbs trásiri and nèsciri, "to go in" and "to go out", from transire and exire. Also, the double l became a double -dd-, for example caballum became cavaddu (horse). Latin had 10 vowels, but Sicilian retained only 5. Long i and short i merged with long e, resulting in i, while long u and short u merged with long o, resulting in u. As a result of these vowel mergers and subsequent sound changes, Latin flōrem developed into Sicilian ciuri (flower), while plēnum developed into chinu (full).
Greek influence in Sicily came in two historical phases: first with the Greek colonies of Magna Grecia, then during Byzantine rule, with Greek continuing in between. Greek contributed vocabulary in several domains, including household life. Naca (crib) is from the Greek nákē, a fleece, because the cradles for newborns were made from stretched sheepskins.
Two centuries of Arab rule influenced the vocabulary of the fields and the kitchen. For example, zágara (orange blossom) comes from zahr, flower. Giuggiulena (sesame seed) derives from the Arabic ǧulǧulān, sesame. Balata, a stone slab, derives from the word balāṭ.
The Normans brought some French vocabulary with them: travagghiari, to work, which in Italian is lavorare. Under Catalan and Spanish influence, additional words entered Sicilian, such as anciova (anchovy) and lástima (a pity, a lament), still meaning exactly that.
Sicilian is spoken by the inhabitants of Sicily and by emigrant populations around the world. My Italian-American students of Sicilian origin are especially interested in this, as they were raised by parents and grandparents who called it "Italian" when in reality it was a mix of Sicilian and Italian.
Sicilian has a larger Spanish and Catalan lexical layer than standard Italian does, but it is not closer to Spanish than to Italian. Most of my students with Sicilian origins come from New York, Canada, Venezuela, Brazil and Argentina.
Who actually speaks it and when
The Sicilian language has not vanished, despite the fact that 82.6% of Italians speak only Italian when communicating with strangers. In my family, Italian was the language of the house, and Sicilian reached me from outside the front door: from old Sicilian neighbours, friends from school, the church. I understand far more than I speak.
With my students coming from the countries listed above, it usually became clear quickly that what they had at home was Sicilian or a mixture of the two. It was used within their families, particularly during the typical Sunday lunch or in everyday situations, but not at work or in formal settings such as meetings. It is used when two or more elderly people are communicating.
Young people, including myself, use it as a sort of seasoning while talking: a word, a curse, an idea that gets explained better in Sicilian. For example, one of my favourite Sicilian words is camurría, and every time I try to translate it into Italian or into another language, something always gets left behind. I drop a Sicilian word like this one into my Italian to get closer to what I have in mind. For me, talking Sicilian is a marked choice.
Italian is the frame and Sicilian words get inserted into it, one at a time, for a reason. For a person in their eighties, a Sicilian-dominant speaker, the marking runs the other way: switching to Italian is the deliberate move. Italian is where I live, Sicilian is somewhere I go.
It is definitely a language
Sicilian and Italian are siblings because of a separate descent from Latin, their own grammar and vocabulary, and limited intelligibility between the two languages. Sicilians understand Italian completely, but Italians understanding Sicilian is a different matter. UNESCO also recognises Sicilian as a standalone Romance language, completely separate from standard Italian.
Sicilian, though, is vulnerable: few children are learning it at home, it faces pressure from standard Italian, it has no official status as a national language and most speakers also speak Italian. Sicilian is not bad or incorrect Italian: if you grew up absorbing Sicilian from your parents or grandparents, bear in mind that they were not speaking incorrect Italian.
In the 13th century, the Sicilian School created the first major literary tradition in an Italian vernacular and developed an elevated form of Sicilian that became foundational to Italian literary poetry. It was adopted as a literary instrument. Giacomo da Lentini, Pier della Vigna and Guido delle Colonne developed a sophisticated literary vernacular based on Sicilian. This was the peak of the Sicilian School, around 1230 to 1250. After the death of Frederick II, the tradition continued under Manfred, and after Manfred's death it carried on in Sicilian-Tuscan poetry under the Angevins.
More than half a century later, Dante recognised the importance of the Sicilian vernacular, which shows how much Sicilian poetry mattered for the history of Italian vernacular literature. It was the prestige model for the development of vernacular poetry, including the Tuscan one.
Should you learn it?
If you want to communicate in Sicily, first of all you should learn Italian. Everybody in Sicily speaks Italian. Sometimes they speak it with a Sicilian accent and Sicilian words in it, but it is still Italian. Honestly, there is no door Sicilian opens that Italian leaves shut, from a practical point of view.
But if you want to learn Sicilian because you are fascinated by it, you could study it afterwards. It is harder to find materials than for Italian. You can start with Gaetano Cipolla's Learn Sicilian / Mparamu lu sicilianu. On Napizia, you can find a dictionary for the Sicilian language that includes verb conjugations and over 12,000 words.
You need to choose a variety of Sicilian, and whichever you choose will differ from what somebody elsewhere in Sicily speaks.
I teach Italian, not Sicilian. You can book my lessons here or you can send me a message.
Overall, Italian gets you the main point of a conversation in Sicily. Sicilian gets you the joke, the aside, which is precisely the layer Sicilian still occupies. If you want to talk to people in Sicily, learn Italian; if you want to communicate with a specific older relative or get more connection to your roots, first learn Italian and then learn Sicilian.
If there is still someone in your family who speaks Sicilian, ask them to talk to you and write down everything they say. These expressions are now yours to carry. If what you want is Italian, the first lesson is free: book it here or send me a message.