fruitless

[Example Sentences]:
1. But I only discovered this after spending some fruitless hours on the relevant forum in the Microsoft community.
2. An intensive but fruitless search organized by the park service was called off.
3. The government and opposition have held two rounds of fruitless reconciliation talks, with a third expected soon.
4. Attempts by users to isolate the cause of the issue have been fruitless so far.
5. On Wednesday, GOP senators spent another frustrating and fruitless day debating and rejecting possible approaches.

[Antonyms]profitable