Antonyms of adj imaginable

1 sense of imaginable

Sense 1
conceivable, imaginable -- (capable of being imagined; "that is one possible answer")

INDIRECT (VIA thinkable) -> unthinkable -- (incapable of being conceived or considered)

Similarity of adj imaginable

1 sense of imaginable

Sense 1
conceivable, imaginable -- (capable of being imagined; "that is one possible answer")
       => thinkable (vs. unthinkable) -- (capable of being conceived or imagined or considered)