Antonyms of adj workable

1 sense of workable

Sense 1
feasible, executable, practicable, viable, workable -- (capable of being done with means at hand and circumstances as they are)

INDIRECT (VIA possible) -> impossible -- (not capable of occurring or being accomplished or dealt with; "an impossible dream"; "an impossible situation")

Similarity of adj workable

1 sense of workable

Sense 1
feasible, executable, practicable, viable, workable -- (capable of being done with means at hand and circumstances as they are)
       => possible (vs. impossible) -- (capable of happening or existing; "a breakthrough may be possible next year"; "anything is possible"; "warned of possible consequences")