Mas has been borrowed from Provençal and Catalan which are both romance languages that belong to the Occitan family.

Provençal is spoken in Provence and Catalan in Pyrénées-Orientales. It is also spoken in Catalonia, Valencia, and the Balearic Islands where it is one of the co-official languages.

It comes from late Latin mansum (“the place where one stays/remains”) which also gave French manoir, masure and maison). In the Middle-Ages mas designated a farmhouse with a particular tenure in the feudal system.¹

The use of the word in French to designate a country house of Provence style dates from the mid 19th century when Provence became fashionable through literary works such as Daudet’s.

_{1. I’m not a historian and really can’t go into details on that topic.}

It is correct that mas comes from the Latin verb “to stay”. “Mansum” is the Past Participle Passive of the Classical Latin verb “manere”(maneo,manere,mansi, mansum).