1. Land under dispute by two opposing parties, especially the field of battle between the lines of two opposing entrenched armies.
2. An area of uncertainty or ambiguity.
3. An unclaimed or unowned piece of land.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.