IPA: /ˈfruːt.ləs.li/
KK: /ˈfruːt.ləs.li/
In a way that does not produce any successful results or benefits.
They searched for the missing keys fruitlessly for hours.
Fruitlessly → It is formed from "fruit" (from Old French *fruit*, meaning the product of plants) and "-less" (meaning without). The word "fruitlessly" means without producing fruit or results, indicating a lack of success or productivity.
Think of 'fruit' as the product of effort, and remember that 'fruitlessly' means without any results or outcomes.