The surname Aimar is of anthroponymic origin and is linked to personal names of Germanic root widespread in the Middle Ages. According to E. De Felice, it is a Piedmontese and Aostan surname that constitutes a variant of Adimari, based on the form Aimar, derived from the Germanic name Adimar. This name had wide circulation in Europe, especially also in the French epic tradition (forms Aimar and Aimer), which may have contributed to its spread in Italy.

For his part, E. Rossoni confirms this origin, noting that it derives from a contracted form of the medieval name Ademarus, composed of the Germanic elements adal ("noble") and mar ("famous"), meaning "noble and famous".

Taken together, both interpretations agree in pointing to a Germanic origin based on a personal name of prestige, spread in northern Italy and consolidated as a surname from the Middle Ages, with variants influenced by both the Italian and French traditions.