It's hard to say without context, however, 'ex' or 'x' most likely refers to an initial position error. Other possibilities include:
A military helicopter
lifer
Jargon refers to specialized language used by a particular group or profession that may not be easily understood by those outside of that group. It can act as a form of shorthand for communicating complex ideas efficiently among members of the same field.
Avoid jargon is the first rule for constructing military correspondence.
Avoid jargon is the first rule for constructing military correspondence.
Avoid jargon is the first rule for constructing military correspondence.
Avoid jargon is the first rule for constructing military correspondence.
A "click" is one kilometer. Military maps are metric.
Chandler
Jargon is language specialized for a certain industry or field.
The police force, computer geeks, the military and the army all use jargon/slang. Doctors and people in the medical field use it as well.
Military jargon / Slang / crude - "Head Mother F*%$er In Charge"