no-man's-land

noun

1. an area between opposing armies, over which no control has been established.
2. an unowned or unclaimed tract of usually barren land.
3. an indefinite or ambiguous area where guidelines and authority are not clear: a no man’s land between acceptance and rejection.
4. (in tennis, handball, etc.) the area of a court in which a player is at a tactical disadvantage, as the area of a tennis court about midway between the net and the base line.

noun

1. land between boundaries, esp an unoccupied zone between opposing forces
2. an unowned or unclaimed piece of land
3. an ambiguous area of activity or thought

n.also no man’s land, “terrain between front lines of entrenched armies,” 1908, popularized in World War I; in use from at least early 14c. as Nonemanneslond, an unowned waste ground outside the north wall of London, site for executions. No man (Old English nanne mon) was an old way of saying “nobody.”