Ciao tutti, is there a word that means “formal jacket”, as in the expression "jacket and tie" or "suit jacket”? Or is “giacca” used for all sorts of jackets, from winter clothing to formal clothing?
Giacca (as reported by Treccani dictionary) is a generic term to indicate a male or female garment, generally made of cloth, but also leather, wool, and similar, covering the upper part of the body till below the waist, provided with sleeves.
giacca s. f. [dal fr. jaque «giaco»].Indumento per uomo o per donna, generalmente di stoffa, ma anche di pelle, di lana a maglia, e sim., che ricopre la parte superiore del corpo fin sotto la vita, ed è fornito di maniche
Giacca e cravatta (jacket and tie) indicates a formal jacket, but sometimes, referring to the type of jacket we use giacca doppiopetto or just doppiopetto to indicate a formal and elegant male jacket.
In everyday speech the term for winter clothing would be giacca a vento or giaccone.
Other variants of giacca like giacchino, giacchetto indicate a smaller and tight female jacket.
giacchétto s. m. [da giacchetta]. – Giacca più piccola e attillata di quella comune, di stoffa o in maglia di lana; in partic., la giacca da donna
In Italy, the equivalent expression of "jacket and tie" or "suit jacket," is generally used for an invitation to a party.
You can use these formulas:
“È gradito l’abito scuro”: gentlemen must wear a formal suit, ladies an elegant dress.
“Dress Code: Black Tie“ (yes, in English) or “Cravatta nera”, that means that gentlemen must wear smoking, ladies an evening gown.
“Dress Code: White Tie“, or “Cravatta Bianca”, that means that gentlemen must wear frac, ladies a long evening gown.
Giacca, as Abarisone said, is used for all sort of jackets and outerwears used to cover the half upper side of the body.
giacca da abito seems fairly common from a google search and I think it's fairly clear.