[uncountable, countable] (formal) an attempt to do something, especially something new or difficult Please make every endeavour to arrive on time. advances in the field of scientific endeavour The manager is expected to use his or her best endeavours to promote the artist's career. The public bombarded the company with complaints in an endeavour to have the price increases revoked. Word Origin late Middle English (in the sense ‘exert oneself’): from the phrase put oneself in devoir ‘do one's utmost’.Extra examples Enthusiasm is a vital ingredient in all human endeavour. He has the ability to achieve success in whatever field of endeavour he should choose. In an endeavour to improve the service, they introduced free parking. Learning a foreign language well can be a lifelong endeavour. She always encourages her children in their artistic endeavours. We will make every endeavour to obtain sufficient supplies. We wish her every success in this endeavour. You must make an endeavour to work harder. the government’s honest endeavours to improve the lives of the poor There have been great advances in the field of scientific endeavour.