TACNA, a town of Peru, in the department of Arequipa, on the left bank of the small river Tacna, about 20 miles from the sea, and 30 N.N.W. of Arica. It is 1700 feet above the sea-level, and stands in a very fertile district. Tacna is the residence of many wealthy foreign merchants, and has an extensive trade. Pop. 8000.