RETHEL, an arrondissement of the department of the Ardennes, in France, extending over 481 square miles. It comprehends six cantons, composed of 124 communes, and contains 59,840 inhabitants. The capital is a city of the same name, situated on the right bank of the Aisne. It contains 900 houses, and 4960 inhabitants, chiefly employed in making coarse woollen goods. Long. 3. 20. E. Lat. 40. 35. N.