Antonyms of adj undoable

1 sense of undoable

Sense 1
unachievable, unattainable, undoable, unrealizable -- (impossible to achieve; "an unattainable goal")

INDIRECT (VIA impossible) -> possible -- (capable of happening or existing; "a breakthrough may be possible next year"; "anything is possible"; "warned of possible consequences")

Similarity of adj undoable

1 sense of undoable

Sense 1
unachievable, unattainable, undoable, unrealizable -- (impossible to achieve; "an unattainable goal")
       => impossible (vs. possible) -- (not capable of occurring or being accomplished or dealt with; "an impossible dream"; "an impossible situation")