Italy is a relative young union of many states that does not exactly speak Italian. How many word you know that coming from some dialect being "Italianized" and even in few dictionary BUT they are only know in few part of Italy?
Just an example:
- waste. Official italian's worlds for that are "spazzatura" or "rifiuti" however in north Italy we commonly use "rumenta" from Genoas/Ancient Republic dialect. In the center-south and south "monnezza" is the most used term.
- posacenere is the most used word for ashtray (ancient portacenere) while in the south nearly anybody use "ceneriera" that coming from spanish "cenicero".
- in Tuscany Melone is not the melon like any other region of Italy, is actually mortadella the famous salami and the melon is "popone". And that's Italian, not dialect.
- again in tuscany "mesticheria" is what the rest of Italy call drogheria (grocery store)
- edicola is the most common word for the place you go to buy newspapers, while in the south is "giornalaio" and sometimes it's used in the center and few north area. In the south edicola is a religious image often sculpted in few ancient houses corners or in church.
- the school bag is normally named "zaino" but sometimes also cartella, while in Lombardy and few part of Piedmont is often named mappetta. All of them are Italian world.
I can continue for long. Language evolve and sometime a language specked by different people from different origins changes. For instance in Swiss, in Italian cantons "fare i fari" or "lapeggiare" (flashing with car headlights) is "bilux" or "biluxare", order something instead of ordinare/fare un ordine is comandare/fare una comanda, mobile phones instead of "cellulare" are named "natel" (that's even do not sound Italian at all). Etc. The same for French in metropolitan French vs Swiss vs Quebec etc.
To really know a language you need to speak it daily with native speaker otherwise you always encounter terms you do not know and even can't find on dictionary or without apparent meaning. Think about English "being at cloud nine", translate it in Italian. It's meaningless. Italian version is "being at seventh sky" that's also meaningless for an English speaker in turn.