DICT.TW Dictionary Taiwan

 Ech·e·lon n.
 1. Mil. An arrangement of a body of troops when its divisions are drawn up in parallel lines each to the right or the left of the one in advance of it, like the steps of a ladder in position for climbing. Also used adjectively; as, echelon distance.
 2. Naval An arrangement of a fleet in a wedge or V form.
 Echelon lens Optics, a large lens constructed in several parts or layers, extending in a succession of annular rings beyond the central lens; -- used in lighthouses.