E. De Felice, E. Rossoni and V. Blunda agree that the surname was formed from the name of Germanic origin Rambaldo, composed of the elements ragan- or ragin- ("counsel," also "divine counsel") and baltha- ("bold, brave").

De Felice specifies that it is of Frankish tradition, documented in Italy from the end of the 8th century in the Latinized forms Ragnibaldus, Ragimbaldus, Raimbaldus and Rambaldus. He notes that the name is common in France as Raimbaud and Rimbaud, and in Provence as Raimbaut and Rambaud. Its original meaning could be "brave, bold in counsel, in decisions."

Rossoni agrees on the etymology and adds that the surname derives, directly or through dialectal variants, from the medieval name Rambaldo, an Italianization of the Germanic Rambald, translatable as "the one who counsels with fierceness." It is the transformation into a surname of the personal names of the founders of the line.

Blunda, for the Sicilian variant, derives it from the Germanic compound Ragin Baltha, with the meaning of "bold through the divine counsel" or "brave of the counselling gods." He mentions as a notable figure Raimbaut de Vaqueiras (c. 1165–1207), a Provençal troubadour at the court of the marquis Boniface I of Montferrat, who accompanied his lord on the Fourth Crusade and composed poems in Provençal, Italian and other languages, preserved as a unique example of the poetic multilingualism of the Mediterranean courtly culture of the beginning of the 13th century.

Blunda also notes that the variant Rebàudi presents the vocalic palatalization characteristic of northern Italian.