[countable] an attempt to do something especially when it is difficult to do. The project was a team effort. a joint/collaborative effort ...

1[uncountable, countable] the physical or mental energy that you need to do something; something that takes a lot of energy You should put more effort into ...

There are four meanings listed in OED's entry for the noun effort, one of which is labelled obsolete. See 'Meaning & use' for definitions, usage, and quotation ...

6 дней назад · EFFORT definition: 1. physical or mental activity needed to achieve something: 2. the result of an attempt to produce…. Learn more.

​to make an effort or try to do something, especially something difficult. attempt to do something I will attempt to answer all your questions.

​in a way that needs little or no effort, and that seems easy. Your presentation must move effortlessly from one point to the next.

needing little or no effort, so that it seems easy. She dances with effortless grace. He made playing the guitar look effortless.

[countable, uncountable] an act of trying to do something, especially something difficult, often with no success. I passed my driving test at the first ...

There is one meaning in OED's entry for the adjective effortful. See 'Meaning & use' for definition, usage, and quotation evidence.

to make an effort or try to do something, especially something difficult attempt to do something I will attempt to answer all your questions.