Uselessly means doing something in a way that serves no purpose or achieves nothing valuable. When you try uselessly to open a locked door by pulling harder and harder, you're wasting effort because the door won't budge no matter how much you pull. When someone argues uselessly with a referee's decision, they're spending energy on something that won't change the outcome.

The word describes actions that don't accomplish what you hope they will. A flashlight with dead batteries shines uselessly. A student might spend hours uselessly reviewing the wrong chapter before a test. A broken umbrella flaps uselessly in the rain, providing no protection at all.

Uselessly often appears when someone recognizes wasted effort: “I uselessly tried to explain the rules to someone who wasn't listening.” It can describe physical actions, like uselessly trying to untangle a hopelessly knotted shoelace, or mental efforts, like uselessly worrying about something completely outside your control.

The word suggests frustration: you're putting in work, but nothing good comes from it.