Antonyms of adj passable

2 senses of passable

Sense 1
passable (vs. impassable) -- (able to be passed or traversed or crossed; "the road is passable")

impassable (vs. passable), unpassable -- (incapable of being passed)
        => unsurmountable, unclimbable -- (incapable of being surmounted or climbed)
        => unnavigable -- (incapable of being navigated)
        => untraversable -- (incapable of being traversed)

Sense 2
adequate, passable, fair to middling, tolerable -- (about average; acceptable; "more than adequate as a secretary")

INDIRECT (VIA satisfactory) -> unsatisfactory -- (not giving satisfaction; "shops should take back unsatisfactory goods"; "her performance proved to be unsatisfactory"; "life is becoming increasingly unsatifactory"; "our discussion was very unsatisfactory")

Similarity of adj passable

2 senses of passable

Sense 1
passable (vs. impassable) -- (able to be passed or traversed or crossed; "the road is passable")
       => navigable -- (able to be sailed on or through safely; "navigable waters"; "a navigable channel")
       => negotiable -- (capable of being passed or negotiated; "a negotiable road")
       => surmountable, climbable -- (capable of being surmounted)
       => traversable, travelable -- (capable of being traversed; "highway crews soon had the roads travelable")

Sense 2
adequate, passable, fair to middling, tolerable -- (about average; acceptable; "more than adequate as a secretary")
       => satisfactory (vs. unsatisfactory) -- (giving satisfaction; "satisfactory living conditions"; "his grades were satisfactory")