A volcanic mountain on the E. coast of Sicily, 10,840 ft. high; a striking feature is the immense ravine, the Val del Bove, splitting the eastern side of the mountain, and about 5 m. in diameter; on the flanks are many smaller cones. Etna is celebrated for its many and destructive eruptions; was active in 1892; its observatory, built in 1880, at an elevation of 9075 ft. above sea-level, is the highest inhabited dwelling in Europe.