In standard usage, the antonym of win is lose, just as the antonym of fail is pass or succeed. But in the version of the English language that commonly sees win preceded by epic, its antonym is fail. This comes from a gamer’s mindset; every endeavour is a contest, but often against a machine, not another person. So if you succeed, it’s a win, but if you don’t, it’s not a loss – you haven’t necessarily been defeated by another person, and you haven’t necessarily lost any money or assets – let alone a lose, a word which has not to my knowledge been nouned yet; it’s a fail because it’s all about you and your worth as a person.
Of these three words, epic, fail, and win, you likely have the impression of seeing win the most often in normal contexts (as opposed to the hyperventilations of adolescents and those who are, at least momentarily, reliving their adolescence). On wordcount.org, fail is in 2,895th place, epic in 10,098th place, and win in 962nd place; in the Corpus of Contemporary American English, there are about twice as many instances of fail as of epic, and more than three times as many instances of win as of the other two combined.
Historically in books, however, if Google ngrams are to be believed, fail has shown up the most, though it has been declining and win increasing steadily to near-convergence. Epic has been fairly steady in third place. But if I search on Amazon.com for books with the keyword epic, I get 24,893 results, many of which focus on history or sports and/or are fiction (and I note with interest that one of the top results is co-authored by someone I know, Arlene Prunkl). If I search fail, I get a mere 4,142 results, tending towards sociology, economics, and epic fails (the top result is from failblog.org). If I search for win, I get 24,341 results, leaning strongly towards business and personal improvement.
And what words do they tend to show up with, respectively? The Corpus of Contemporary American English gives me proportions, poem, battle, story, struggle, tale, and journey to go with… guess? Epic, of course. Fail is most often seen after often, and also after without, and is frequently followed by to recognize, to understand, and to meet (standards, a challenge, obligations, et cetera). And win? Win over is very common, and going to win quite common too – of course won and winning are evaluated separately. What do you win? A war, a game, an election, a championship… you know, the usual stuff.
But win is the most versatile of the three. It is well established as both a noun and a verb (both for as long as there has been an English language). It comes from a word meaning “work, labour, strive, obtain”. It shows up in assorted terms and phrases, from winsome to you win some, you lose some. The particular perversity of English phonology and orthography have led to its having a stronger flavour of when than of wind (/wɪnd/, “moving atmosphere”), and no real taste anymore of wind (/waɪnd/, “increase torsion by turning”). There are a few names that smack of it, including Winston, Winnifred, Ashwin, and especially the family name Wynn – which, among other things, is the name of a casino hotel in Las Vegas.
But what really makes win special for an English language geek like me is that wynn is also the name of a letter that English used to have – a runic letter (ƿ) used in Old English to represent the first sound in win. It’s no great surprise that wynn went out of use when w became available; it looked too much like p and y and thorn (þ, another runic borrowing we used to represent a sound we now spell th; Icelandic still uses it). Ha – orthography fail. Well, the chances of winning have improved with the change: they used to look thin, but now the word declares, “double you in”! Win FTW! (FTW = “for the win”.)