"Upvote" vs. "up vote" vs. "up-vote"

Solution 1:

Within the nomenclature of this site, upvote seems to be the accepted term.

Otherwise, you could go for up-vote or vote up but not up vote.

Upvote and the hyphenated up-vote work because they are compounds and create a new verb. Though the resulting word is not in a dictionary, it works because it follows logical/existing morphology patterns, whereby the prefix 'up-' modifies the verb 'vote'.

Up vote with spaces does not work however, because it confuses the syntax of the sentence.

Solution 2:

I would also add that "up vote" throws off my reading stride because saying "I up ..." is improper english and my brain has to make a quick mental note that someone is coining a usage.

"Upvote" might be unrecognizable to someone not familiar with forums such as this, while "Vote up" would be understandable.

"Up-vote" actually strikes me as a noun, not a verb. At least that's how I turn a phrase into an adjective or noun, such as "the man-in-the-middle attack", or "a man-on-the-street interview".

I would vote for "up-vote" to answer the original question: it sounds more natural to my geeky & American ears. If I analyze it closely, I would view it as a noun being used as a verb. (Sorry, I don't always know the proper technical words to describe such things.)

Solution 3:

I posted a question on Meta Stack Overflow, "Can we downvote “down-vote” and “up-vote” in the Help Center and the associated tags?" where I linked to the accepted answer to by Karl, and did some additional research which found that dictionaries and Meta Stack Overflow itself favour "downvote" and "upvote" over "down-vote" and "up-vote" respectively.

As this question asks (emphasis mine)

Should I use "upvote", "up vote", or "up-vote" on SE sites? What about "downvote"?

the findings in my question are relevant:

• Searches for "downvote", "upvote", "down-vote", and "up-vote" filtered by the creation date on Meta Stack Overflow show the common usage is unhyphenated:

  

  

Sadly I couldn't construct an Ngram comparison for the terms - it seems that hyphenated words are difficult to search for.

The usages of "downvote" and "upvote" outnumbers the usages of "down-vote" and "upvote" by more than 4:1, so I would say that "downvote" and "upvote" (which are in some dictionaries, e.g. 1, 2, 3, 4) are perfectly fine and in common usage — on Meta Stack Overflow, where the data for the graphs came from, at least — I have no reason to assume that the rest of Stack Exchange will be any different.