V. Blunda notes that the surname comes from the Greek eygenès, "well-born, noble", where the Greek upsilon is realised as u. It is a compound of eu-, "well", and genes, "lineage". According to Blunda, the surname arose as the crystallisation of the baptismal name applied to an ancestor in the Byzantine hagiographic tradition, with presence in Sicily.

A. Bongioanni agrees on the Greek origin with the sense of "well-born" and highlights that the name was borne by twenty-three saints, among them a pope of the 7th century. In Friuli, the derived forms are Genét and Genuzio, this last also being a given name, although practically unknown in that region. Bongioanni also mentions the forms Genin and Geninatti, and the derived place name Gignod, in the Aosta area.

Bongioanni observes that, through a phonetic crossing between eugeniu and ingeniu, the forms Ingegnóli —from the Lombard word ingegnō— and Ingegnatti, documented in the Piedmont area although possibly not autochthonous, are linked with this surname. He adds the surname Ingegneri —known through Angelo Ingegneri, friend of the poet Tasso— and proposes that a Lombard ingegnatt could exist, analogous to ragionatt, with the sense of "accountant". The word "engineering" is of Italian origin and was adopted in almost all European languages. As documentary support, Bongioanni cites an Incignatus used as a surname in documents of Lodi towards 1387, and a Johannes Ingenerius who was bishop of Capodistria between 1576 and 1600.