Definition of open:
"turn left after the second open door."
(v) :
to make something accessible or removing an obstacle to something being accessible; to
bring up (a
topic)
"turn the doorknob to open the door."
(n) :
a
sports event in which anybody can
contest; as, the Australian Open; a wire that is broken midway
"the electrician found the open in the circuit after a few minutes of testing."