History is replete with heroes and would-be heroes going to extraordinary lengths to achieve lofty goals. Many of them did not actually succeed, but their travails have been recorded as a monument to human determination and ingenuity. In English, we might call such attempts endeavors. Or would we call them endeavours?
Endeavor as verb:
Endeavor as noun:
Use of endeavor:
Use of endeavour:
The contestants were mentored by the people who’d nurtured the musical endeavours of Westlife, Ozzy Osbourne and, er, Zig and Zag – Louis Walsh, Sharon Osbourne and Simon Cowell respectively – and who would repeatedly tell them that the key was working hard and trying their best every week. –The Guardian
Endeavor or endeavour:
Endeavor and endeavour are the American and British variants, respectively, of a plural noun that refers to effortful or time-consuming attempts to do something. Endeavor is the American version of this word. Endeavour is the British version. Endeavour, with its extra U, is standard in the United Kingdom, which also has a U in it. The shared letter is your clue for the proper usage context of the word endeavour.