Fougax et Barrineuf lies at the junction of the St Nicolas river, which flows down from Montségur, and the Hers river, which comes from the Pays de Sault in the Aude region. This long valley is thickly forested with oak and fir trees.

The demarcation between the two former parishes of Fougax and Barrineuf followed the medieval boundaries of the two former Lévis seigneuries until the early 17th century, when they were merged. The suffix "ax", from the Latin "asqua", reflects the village's major characteristic: water, omnipresent at the basins, washhouses and fountains, materializing the three main communal boundaries when it resurfaces underground.