The name of Ayguatébia appears in 958 as Aqua tebeda, immediately followed in 959 by Aquatepida. Villa Aque tepida is used during the 11th century and Aiguetevia is found in 1392. From the 17th century and on, the common forms are Aiguetebia and Ayguatebia. The modern spelling in Catalan is Aiguatèbia, but the traditional spelling, Ayguatèbia, should be preferred.
The name of Talau appears in 874 as Villa Talatio and in 876 as Talacho. Talazo, Talaz and Talaxo are used during the 10th century. Talau appears in the 13th century and is used since.
The name of Ayguatébia comes from the Latin aqua tebeda, meaning lukewarm water, in relation with warm springs found in Ayguatébia.
The name of Talau comes from a pre-Latin radical, Tal or Tala, meaning a small plateau found above a cliff or a hill, which corresponds to the situation of the village of Talau, located above the valley of the Cabrils river.