ADJECTIVE (2)

1. not made more desirable or valuable or profitable; especially not made ready for use or marketing;
- Example: "taxes on unimproved land are low"
- Example: "unimproved dirt roads"

2. (of land) not cleared of trees and brush; in the wild or natural state;
- Example: "a farm with 50 acres of unimproved and 68 acres of improved land"
- Example: "unimproved woodlands"

The Collaborative International Dictionary of English v.0.48:

Unimproved \Un`im*proved"\, a.
   1. Not improved; not made better or wiser; not advanced in
      knowledge, manners, or excellence.
      [1913 Webster]

   2. Not used; not employed; especially, not used or employed
      for a valuable purpose; as, unimproved opportunities;
      unimproved blessings. --Cowper.
      [1913 Webster]

   3. Not tilled, cultivated, or built upon; yielding no
      revenue; as, unimproved land or soil.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unimproved
    adj 1: not made more desirable or valuable or profitable;
           especially not made ready for use or marketing; "taxes on
           unimproved land are low"; "unimproved dirt roads" [ant:
           improved]
    2: (of land) not cleared of trees and brush; in the wild or
       natural state; "a farm with 50 acres of unimproved and 68
       acres of improved land"; "unimproved woodlands"