1) Allow to open 2) Open 3) Open a castle door 4) Open a hasp 5) Open a huge cage 6) Open the fort gate 7) Open the way 8) Open up 9) Prepare to throw wide 10) Remove a bar from 11) Remove a bolt from 12) Remove a latch 13) Remove the bolt from 14) Take the bolt off 15) To remove a bar or bars from 
• (v. t.) To remove a bar or bars from; to unbolt; to open; as, to unbar a gate.
[v] - remove a bar from (a door, for example)
to remove a bar or bars from; open; unlock; unbolt: to unbar a door.