WordNet sense 1 (a clear or unobstructed space or expanse of land or water):

clear

WordNet sense 2 (where the air is unconfined):

out-of-doors, outdoors

WordNet sense 3 (information that has become public):

surface

WordNet sense 4 (not defended or capable of being defended):

assailable, undefended, undefendable

WordNet sense 5 (susceptible to attack):

vulnerable

WordNet sense 6 (possibly accepting or permitting):

capable, subject, subject

WordNet sense 7 ((often followed by `of' or `to') yielding readily to or capable of):

susceptible

WordNet sense 8 (start to operate or function or cause to start operating or functioning):

open up

WordNet sense 9 (not belonging to or not allowing affiliation with a trade union):

nonunion

WordNet sense 10 (afford access to):

afford, give

WordNet sense 11 ((of textures) full of small openings or gaps):

loose

WordNet sense 12 (of textures that are rough to the touch or substances consisting of relatively large particles):

coarse, harsh

WordNet sense 13 (not brought to a conclusion; subject to further thought):

undecided, undetermined, unresolved

WordNet sense 14 (still in doubt):

unsettled

WordNet sense 15 (ready or willing to receive favorably):

receptive

WordNet sense 16 (with no protection or shield):

exposed

WordNet sense 17 (lacking protection or defense):

unprotected

WordNet sense 18 (not private; open to or concerning the people as a whole):

public

WordNet sense 19 (obvious to the eye):

visible

WordNet sense 20 (open and observable; not secret or hidden):

overt

WordNet sense 21 (not closed in our surrounded or included):

unenclosed

WordNet sense 22 (with the mouth wide open indicating boredom or sleepiness):

yawning

WordNet sense 23 ((used of eyes) fully open or extended):

wide

WordNet sense 24 (with the mouth wide open as in wonder or awe):

agape, gaping, agape

WordNet sense 25 (made open or clear):

opened

WordNet sense 26 (slightly open):

ajar

WordNet sense 27 (affording unobstructed entrance and exit; not shut or closed):

unfastened

WordNet sense 28 (spread out or open from a closed or folded state):

spread, unfold, spread out

WordNet sense 29 (not constricted physically or by extension psychologically):

unconstricted

WordNet sense 30 (openly straightforward and direct without reserve or secretiveness):

candid, heart-to-heart

WordNet sense 31 (characterized by an inability to mask your feelings; not devious):

artless, ingenuous

WordNet sense 32 (obtainable or accessible and ready for use or service):

available

WordNet sense 33 (full of activity or engaged in continuous activity):

active