The authors agree that this surname derives from the Germanic personal name Wido / Wuido. The Germanic root admits differing interpretations: A. Bongioanni points to the roots witu and wide, meaning "wood" or "forest", the semantic equivalent of the Latin Silvius; F. Miranda adds that it may also derive from Wuida, with the sense "distant", possibly alluding to a family living in isolation in the forest; V. Blunda proposes the root wida with the sense "wide, vast", or else a reduced form of compound personal names.

Bongioanni warns that in some derivatives this name is confused with Vito. Among the derived forms, he mentions Tuscan surnames such as Guidi, Guidiccioni and Guidarelli; the Friulian Vidizzon; and forms distributed across various parts of Italy such as Guidetti, Guidoni, Guidotti, Ghidini, Ghidella, Vidoni and Guidazzi. Blunda further notes the variants Guida, Guitto and Guy as adaptations of the personal name in different medieval linguistic traditions.

Miranda describes a presence extending throughout Italy, with a diffusion in regions such as Apulia, Calabria, Piedmont, Liguria, Lombardy, Lazio, Campania, Sicily, Veneto and Tuscany. Blunda highlights the connection with Guido d'Arezzo (c. 991–1050), the Benedictine monk who around 1025 invented the modern system of musical notation on a four-line staff and the naming of the notes —ut, re, mi, fa, sol, la— drawn from a Latin hymn to Saint John the Baptist, an advance that made possible the written transmission of European polyphonic music.