Antonyms of adj gainful

1 sense of gainful

Sense 1
gainful, paid, paying -- (yielding a fair profit)

INDIRECT (VIA profitable) -> unprofitable -- (producing little or no profit or gain; "deposits abandoned by mining companies as unprofitable")

Similarity of adj gainful

1 sense of gainful

Sense 1
gainful, paid, paying -- (yielding a fair profit)
       => profitable (vs. unprofitable) -- (yielding material gain or profit; "profitable speculation on the stock market")