to start or begin a meeting, speech, performance, etc.

to facilitate the availability or accessibility of something

to become available for use or access

to initiate action in a card game by making the first move

to have a passage, entryway, or outlet that allows access to a space or area

to make the contents of a file or an application visible on a computer screen

affording free passage or access

with no protection or shield

open to or in view of all

used of mouth or eyes

not having been filled

accessible to all

(of textures) full of small openings or gaps

not enclosed or restricted

not defended or capable of being defended

(set theory) of an interval that contains neither of its endpoints

without undue constriction as from e.g. tenseness or inhibition

not sealed or having been unsealed

not brought to a conclusion; subject to further thought

ready or willing to receive favorably

open and observable; not secret or hidden

not requiring union membership

possibly accepting or permitting

affording free passage or view

where the air is unconfined

information that has become public

a tournament in which both professionals and amateurs may play