IPA: /ɪnˈdɛvər/
KK: /ɪnˈdɛvər/
An attempt to achieve a goal or a serious effort to do something.
Her endeavour to learn a new language was impressive.
Endeavour comes from the Old French 'endevoir' (meaning to put in effort or to strive), which is derived from 'en-' (meaning to make) and 'devoir' (meaning duty or obligation). The word 'endeavour' means to make an effort or to strive towards a goal, reflecting the sense of putting in effort towards one's duty or task.
Think of 'making an effort' ('en-') towards fulfilling a 'duty' ('devoir') — that's why endeavour means to strive or put in effort.