open for discussion

:  having no enclosing or confining barrier :  accessible on all or nearly all sides

:  being in a position or adjustment to permit passage :  not shut or locked

:  having a barrier (such as a door) so adjusted as to allow passage

:  to move (something, such as a door) from a closed position

:  to make available for entry or passage by turning back (something, such as a barrier) or removing (something, such as a cover or an obstruction)

:  to make available for or active in a regular function

:  opening

:  open and unobstructed space: such as

:  open air

:  consideration of a question in open and usually informal debate

:  a formal treatment of a topic in speech or writing