Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

unlatched
     adj : not firmly fastened or secured; "an unbarred door"; "went
           through the unlatched gate into the street"; "an
           unlocked room" [syn: {unbarred}, {unbolted}, {unlocked},
            {unsecured}]