ech·e·lon 
(ĕshə-lŏn′)
(ĕshə-lŏn′)n.
1.
a. A formation of troops in which each unit is positioned successively to the left or right of the rear unit to form an oblique or steplike line.
b. A flight formation or arrangement of craft in this manner.
c. A similar formation of groups, units, or individuals.
2. A subdivision of a military or naval force: a command echelon.
3. A level of responsibility or authority in a hierarchy; a rank: a job in the company's lower echelon.
4. Physics A special form of diffraction grating that resembles a flight of stairs of equal heights and equal widths.
tr. & intr.v. ech·e·loned, ech·e·lon·ing, ech·e·lons
To arrange or take place in an echelon.
[French échelon, from Old French eschelon, rung of a ladder, from eschiele, ladder, from Late Latin scāla, back-formation from Latin scālae, steps, ladder; see skand- in the Appendix of Indo-European roots.]