Fanslation is a portmanteau of fan and translation. Unsurprisingly, it refers to a translation by fans of a work as contrasted against an official and/or professional translation. In the terrible swirling cauldron of anime fandom there is a desperate, insatiable need for the next chapter or episode. Since official translations are driven by commercial realities they are often slow in coming through official channels because the publishers are uncertain about the commercial viability of a work, when it's even considered at all. In either case the work has already shown up on the internet and been passed around various fan sites within two hours of its official release and fanslations likely follow in short order. While not every (English) fanslation comes from Japanese or Korean sources they're the main sources of such media.
Fanslations are, on average, bad to the point of being a running joke. In a world with Google translate this was bound to be the case but the kinds of problems that show up seem to point to an almost willful misunderstanding of what a translation is supposed to do. Of the few fanslations I personally have come across the grammar and syntax, while technically correct, were so tortuously different from how English is actually spoken that I can only assume that it's some kind of attempt to preserve sentence structure from the original language. Combine that with idioms that aren't adapted and the general weirdness of contrasting cultures and many fanslations read like a fever dream. The increasing normalization of anime/manga in American culture have actually seen a bit of a dip in fanslations as the translation industry has recognized and responded to obvious demand for more translation with faster deployment.
IRON NODER THE THIRTEENTH