Mentonasc (Mentonasco in Italian, Mentonnais in French), is a transition dialect historically in and around Menton, France. It is generally classified as Occitan, with some strong features from the neighbouring Intemelian Ligurian dialect spoken from Monaco to San Remo.
The Mentonasc shows some transition features to the Ligurian language, but is traditionally assigned to the Occitan language (Provençal Niçard dialect).
In the Archivio Glottologico Italiano XII, 1890/92, pp. 97–106 John Bruyn Andrews wrote that the dialect of Menton is in the middle between the Ligurian and Provençal dialects.
When the area of Menton was part of the Republic of Genoa and later of the Kingdom of Sardinia, the Mentonasc was used in all the coastal area between Monaco and Ventimiglia. It was a local version of the historical intemelio, a medieval western ligurian dialect.
In the 19th century the Mentonasc was used in the territories of the Free cities of Menton & Roquebrune, an independent little State created in connection with the Italian Risorgimento.