sinfoniettaPronunciation: /ˌsɪnfəʊnɪˈɛtə/Definition of sinfonietta noun Music a short or simple symphony. a small symphony orchestra: [as name]:the Bournemouth SinfoniettaOrigin:Italian, diminutive of sinfonia (see sinfonia)sinfonietta in other Oxford dictionaries Definition of sinfonietta in the US English dictionary