echelon

First recorded in 1790–1800; from French échelon, originally “rung of a ladder,” from Old French eschelon, equivalent to esch(i)ele “ladder” (from Latin scāla + -on noun suffix; see scale³)

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.