ech·e·lon /ˈɛʃəˌlɑn/
 梯形,梯陣,梯次編隊(vt.)排成梯隊(vi.)形成梯隊
 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.
 Ech·e·lon v. t. Mil. To place in echelon; to station divisions of troops in echelon.
 Ech·e·lon, v. i. To take position in echelon.
    Change direction to the left, echelon by battalion from the right.   --Upton (Tactics).
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 echelon
      n 1: a body of troops arranged in a line
      2: a diffraction grating consisting of a pile of plates of
         equal thickness arranged stepwise with a constant offset