echelon

1790–1800; < French échelon, orig. rung of a ladder, Old French eschelon, equivalent to esch(i)ele ladder (< Latin scāla; see scale³) + -on noun suffix

Echelon comes from the French échelon, a word whose literal meaning is “rung of a ladder.” Initially it was confined to military use, to refer to a step-like formation of troops.
Ironically, while echelon entered English in a military context, it was the first and second World Wars that extended the meaning to other, nonmilitary, sectors. During World War I, the term took on a more generalized sense of a “level” or “subdivision”; World War II broadened echelon’s usage to describe grades and ranks in professions outside the military.
At the same time, English speakers started using echelon to classify institutions or persons they held in high esteem by referring to them as part of the “upper” or “top” echelon. With this in mind, the phrase “social climber” conjures up the image of people who wish to ascend through the various ladder rungs of society until they reach the top.

—Row echelon form: In linear algebra, a simplified form of a matrix in which each non-zero row has more leading zeros than the previous row.
—ECHELON: Code name of a global surveillance system developed by the United States National Security Agency (NSA). It operates by intercepting and processing international communications transmitted via communications satellites.
—Third Echelon: A fictional sub-group of the NSA created by Tom Clancy in his Splinter Cell book series.