Wordnet 3.0
ADJECTIVE (1)
1. 
 free from impediment or obstruction or hindrance; 
- Example: "an unobstructed view"
The Collaborative International Dictionary of English v.0.48:
Unobstructed \Unobstructed\
   See obstructed.
WordNet (r) 3.0 (2006):
unobstructed
    adj 1: free from impediment or obstruction or hindrance; "an
           unobstructed view" [ant: obstructed]
Moby Thesaurus II by Grady Ward, 1.0:
27 Moby Thesaurus words for "unobstructed":
   bald, bare, clear, cleared, disclosed, disembarrassed, exposed,
   free, naked, open, unburdened, unclogged, unclosed, uncovered,
   unembarrassed, unencumbered, unhampered, unhandicapped, unhidden,
   unhindered, unimpeded, unladen, unprevented, unrestricted,
   unstopped, untrammeled, wide-open