Meaning of NuGet

Look here.

Seems it was voted on.
It's a bit hard to say (maybe I didn't look into it well enough) but -- especially since pronunciation is "New Get" -- basically:

NuGet: A new way to get libraries.

Nu stands for -> "Nubular / Nu". Around mid-2010 Dru Sellers and gang (including Rob Reynolds aka @ferventcoder) built the fantastic “nu[bular]” project; this was itself a ruby gem. Team Nubular developed. In October 2006 Nu became Nu v2, at which point it became NuPack; The Epic Trinity of Microsoft awesomeness – namely Scott Guthrie, Scott Hanselman, and Phil Haack – together with Dave Ebbo and David Fowler and the Nubular team took a mere matter of months to create the first fully open sourced project that was central to an MS product – i.e., VisualStudio which was accepted into the ASP.Net open source gallery in Oct 2006

It’s referred to as NuPack in the ASP.MVC 3 Beta release notes from Oct 6 2010 but underwent a name change due to a conflict with an existing product, NUPACK from Caltech.

NuGet! (finally) There was a vote, and if you look through the issues listed against the project in codeplex you can see some of the other suggestions.

(Notice how none of the names available in the original vote are “NuGet”..)

Finally we have NuGet! The associated codeplex work item actually originally proposed “Nugget”, but that was change to NuGet. Here's the link- https://www.robinosborne.co.uk/tag/nupack/