The authors agree that this surname derives from the personal name of Germanic origin, with a Lombard tradition, Tedaldo, whose compound root is formed by the elements theuda- ("people") and wald- ("powerful, strong"), with the approximate meaning of "powerful among his people". E. De Felice documents the name from the year 715 under the forms Teudaldus and Teodoald, and notes that the form Tedaldus appears as early as the 10th–11th centuries.

E. Rossoni contributes that the name is attested in the Codice Diplomatico della Lombardia Medioevale in a deed of Bergamo of 1042, and that its transformation into a surname is documented in Vimercate in 1168 and in a letter of 1506 from Lattanzio Tedaldi to Niccolò Machiavelli. Rossoni places the surname Tedaldi mainly in the Forlì and Parma areas, while the variants Tedoldi are recorded in the Brescia area, and Teoldi, of very scarce presence, in the Bergamo area. De Felice, for his part, notes that the forms in Tea- and Tedoldi are characteristic of the north-west of Italy, and also highlights a presence in Tuscany.