E. Rossoni considers that this surname derives from a nickname based on the Arabic term haddām, meaning "servant", and places it as a very rare surname of probable Sicilian origin.

V. Blunda agrees in noting Sicily as the region of origin, but proposes a different etymology: according to this author, the surname comes from the Sicilian dialectal word gaddèmi, meaning "vile man". It would have arisen as a nickname applied to someone considered morally despicable, a habitual practice in the formation of Sicilian mocking surnames, where the judgements of the community could become hereditary family designations.