FUTILE

You often do certain activities and later realize that they were hopeless or useless, or were not worth doing. Futile, basically means doing something that is not capable of producing any result, or something that is not important. 

For example, when your father is angry and yelling, you try to cool him down but realize that it's not helping, that means your attempt to cool him down was futile. It means you do something that was not worth attempting or something totally hopeless and not successful. As the word futile describes something that is useless or hopeless, it is an adjective.

Example 01 : Conducting research and development for the new mobile phone proved futile, as it failed in the market after it's grand launch. 
Ex 02 : After a mile or so, the thief realized that his attempt to outrun the police was futile, and he finally surrendered. 
Ex 03 : Practicing for my Math exam was futile as I couldn't solve the paper in the examination.
Ex 04 : When Rosie is discussing about her career plans, Mary's futile comments begin to annoy her.
Ex 05 : Mother shouted at her son, "Don't waste your time on futile activities, like talking on the phone with your friends before the exams."
Ex 06 : Expecting our bus to come on time, is futile, as it is always late.
Ex 07 : Investing in property now is futile, as prices are expected to drop in a few months.
Ex 08 : Requesting the boss for a salary raise now futile, as he is upset due to my long absenteeism at work.
Ex 09 : Jack told Mary, "Giving you a call is futile, you never answer it as you are always busy."
Ex 10 : Asking our neighbors to lower down the sound of their music system is futile, they always play it loud.
Ex 11. It's futile trying to persuade John to visit Gym, he is just growing like a sack of potatoes.