Antonyms of adj untenable

1 sense of untenable

Sense 1
indefensible, untenable -- ((of theories etc) incapable of being defended or justified)

INDIRECT (VIA unreasonable) -> reasonable, sensible -- (showing reason or sound judgment; "a sensible choice"; "a sensible person")

Similarity of adj untenable

1 sense of untenable

Sense 1
indefensible, untenable -- ((of theories etc) incapable of being defended or justified)
       => unreasonable (vs. reasonable) -- (not reasonable; not showing good judgment)