1.of no use; not working or not achieving what is needed
Without fuel, the vehicles will become useless for moving supplies.
It's useless to speculate without more information.
2.not at all good at doing something
Don't ask me to add it up - I'm useless at maths.
She's very good at methodical work, but useless when there's a lot of pressure.
3.of no value; worthless
With dead batteries, the flashlight was useless.