Antonyms of adj differentiable

1 of 2 senses of differentiable

Sense 2
differentiable -- (capable of being perceived as different; "differentiable species")

INDIRECT (VIA distinguishable) -> indistinguishable, undistinguishable -- (not capable of being distinguished or differentiated; "the two specimens are actually different from each other but the differences are almost indistinguishable"; "the twins were indistinguishable"; "a colorless person quite indistinguishable from the colorless mass of humanity")

Similarity of adj differentiable

2 senses of differentiable

Sense 1
differentiable -- (possessing a differential coefficient or derivative)

Sense 2
differentiable -- (capable of being perceived as different; "differentiable species")
       => distinguishable (vs. indistinguishable) -- (capable of being perceived as different or distinct; "only the shine of their metal was distinguishable in the gloom"; "a project distinguishable into four stages of progress"; "distinguishable differences between the twins")