Not built on or cultivated so as to increase in value. Used of land.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "unimproved" in a sentence
"The other third of the improved land and a considerable portion of that half of the farm area known as unimproved land are utilized as pasture for domestic animals."
"Our development has so much spraying for things that probably don't need to be sprayed that the displays are on the lame side, but trips to "unimproved" regions can be spectacular."
"The cave is "unimproved", which means no lights other than what you bring with you, the occasional interpretive sign and a set of metal steps to help you make the initial descent."