---

Endeavor vs. Endeavour
If you are asking whether "endeavor" or "endeavour" is a misspelling, then you should know from the very beginning that the answer is no. They are both considered correct spellings. But does this also mean that their meanings are the same?
Find out if you can use both "endeavor" and "endeavour" in the same contexts and what recommendations we have for you when using these words.
Endeavor vs. Endeavour
"Endeavor" and "endeavour" refer to the same thing, to the same intense attempt and determination to do something. The major factor generating their spelling differences is represented by the English vocabularies that prefer them. More exactly, "endeavor" is the US spelling, and probably most frequently used, whereas "endeavour" is mostly used in formal UK English.
Otherwise, there is another slight difference that occurs between these two, which refers to the contexts in which you can use one, but not the other. Let's take a closer look to the situations where you should use "endeavor" and "endeavour" and where you shouldn't.
When do we use "endeavor"?
"Endeavor" is the US spelling of the word and it is only used as a verb, referring to the action of trying very hard to do something. Definitely choose to use this word if you are talking in American English.Example: Even if he wouldn't let me, I will still endeavor to help him. - "endeavor" refers to the action of trying very hard to do something.
When do we use "endeavour"?
Even though it's used less frequently than "endeavor", as it is somehow more formal, "endeavour" is commonly preferred in British English. In addition to this, not only can you use it as a verb, with the same meaning explained above (putting effort, struggling to do something), but also as a noun, referring to the efforts of an artist, for example, within an enterprise.
Example 1: I endeavour to support you even when you refuse my help. - referring to the action of struggling to do something.
Example 2: Everyone appreciated his artistic endeavour. - as a noun, "endeavour" refers to the efforts someone puts into something.
Conclusion
Even though their meanings are almost identical, here are the slight differences you should remember in order to use these words correctly: "endeavor" is the US spelling, only used as a verb, whereas "endeavour" is the UK spelling that can be used both as a verb and as a noun.