BOSA, a city on the western coast of the island of Sardinia, in a fine valley on the northern bank of the Termo. It is well built and paved; is the see of a bishop; and has a cathedral, a diocesan seminary, and several schools. The harbour is safe, being sheltered by the islet of the same name. Pop. 6000. Long. 8. 25. 31. E. Lat. 40. 16. 40. N.