Antonyms of adj cost-effective

1 sense of cost-effective

Sense 1
cost-efficient, cost-effective -- (productive relative to the cost)

INDIRECT (VIA efficient) -> inefficient -- (not producing desired results; wasteful; "an inefficient campaign against drugs"; "outdated and inefficient design and methods")

Similarity of adj cost-effective

1 sense of cost-effective

Sense 1
cost-efficient, cost-effective -- (productive relative to the cost)
       => efficient (vs. inefficient) -- (being effective without wasting time or effort or expense; "an efficient production manager"; "efficient engines save gas")