^No, what he's asking is whether the prefix is an acronym, N. U. for "New Universe."
From what I can tell, "nu-" is an informal or deliberately incorrect spelling of "new" which originated in the 20th century in reference to music genres, like "nu-metal." At least, that's what the Internet dictionaries say. It always struck me as the kind of cutesy misspelling that marketers create for product names. Personally I find it rather annoying.
We need a better long-term name for the new films' universe. The makers of the 2009 film gave us this nice, handy label "Prime" for the original continuity, but we don't have anything of comparable simplicity and clarity for the new continuity -- or anything as catchy as "the Mirror Universe." "Abramsverse" is a clunky coinage, and it's possible that the timeline will continue to be explored by other creators after Abrams and Bad Robot have moved on to other things. And it won't be a new -- or "nu" -- universe forever, so that label doesn't seem like it'll have staying power. Memory Alpha's preferred label for it is "the alternate reality," but that's so generic. Alas, I can't think of a better term. The post-Nero universe? The Red Matter timeline?