1. 
[syn: unbarred, unbolted, unlatched, unlocked, unsecured]
The Collaborative International Dictionary of English v.0.48:
Unlatch \Un*latch"\, v. i. [imp. & p. p. Unlatched; p. pr. &
   vb. n. Unlatching.] [1st un- + latch.]
   To open or loose by lifting the latch; as, to unlatch a door.
   [1913 Webster]
WordNet (r) 3.0 (2006):
unlatched
    adj 1: not firmly fastened or secured; "an unbarred door"; "went
           through the unlatched gate into the street"; "an unlocked
           room" [syn: unbarred, unbolted, unlatched,
           unlocked, unsecured]