Military parlance is the vernacular used within the military and embraces all aspects of service life; it can be described as both a "code" and a "classification" of something. Like many close and closed communities, the language used can often be full of jargon and not readily intelligible to outsiders—sometimes this is for military operational or security reasons; other times it is because of the natural evolution of the day-to-day language used in the various units.

For example: "Captain, this situation is 'Scale A'", "Scale A" being an army's parlance for "This situation requires the closest of attention and resources and all members of relevance should be present."

The military has developed its own slang, partly as means of self-identification. This slang is also used to reinforce the (usually friendly) interservice rivalries. Some terms are derogatory to varying degrees and many service personnel take some pleasure in the sense of shared hardships which they endure and which is reflected in the slang terms.