The old name of the mountain was Rognosa di Galambra, which derived from the secondary valley of Galambra (a tributary of Dora Riparia). It was then renamed by the geologist Martino Baretti, author of the first documented ascent to the summit, in order to avoid confusions with two neighboring Rognosas, Rognosa d'Etiache and Rognosa del Sestriere. The new name was chosen to honour Germain Sommeiller, the civil engineer which directed the construction of the Fréjus Rail Tunnel between Savoy and Piedmont.