TREVOU, an arrondissement in the department of the Ain, in France, extending over 592 square miles. It contains seven cantons and 111 communes, with 77,530 inhabitants in 1836. The capital, which is the city of the same name, stands on the left bank of the Saone, on a range of hills covered with the finest vineyards. It contains 3559 inhabitants, who make many parts of the works of clocks and watches, and draw wire of gold and of silver. Long. 5. 5. 45. E. Lat. 45. 56. 42. N.