According to Wikipedia:
In rhetoric, anthimeria […] involves using one part of speech as another part of speech, such as using a noun as if it were a verb: “The little old lady turtled along the road.” […] Other substitutions could include an adjective used as a noun, as in “She dove into the foaming wet,” interjection as verb, as in “Don't aha me!”, a verb as a noun, as in “Help! I need some eat!” and so on.
Anthimeria isn’t entirely a new word for me; I mentioned it in passing in 1999 in colum rrr, about rhetorical devices. But I feel like anthimeria has become a particularly useful concept in recent years, as the internet starts to weird language even further than it’s been weirded in the past.
…Well, I should qualify that; I’m not sure whether to say that phrases like “because internet” and “don’t @ me” and “all the feels” are anthimeria as such. They do seem to involve changing one part of speech into another (such as changing because from a conjunction to a preposition), but I feel like other things are going on along with those changes. But even so, I feel like anthimeria is a relevant concept.
(I went looking for what Language Log has to say about prepositional because, and I found a 2014 Pullum post about it—but he spends so much of the post calling lexicographers stupid brainless plagiarizing idiots that I was really put off by the post and don’t want to link to it.)
By the way, apparently the linguistic process of transforming a word from one part of speech into another is called conversion, zero derivation, or functional shift. (But I may be misusing those terms. I got them from an article titled “Linguistic Conversion in Grammar.”)
(The idea of parts of speech is itself a little bit muddy; for more on that, see column oo.)