In the interim since this Wishlist topic was started, Rombbbbb has produced a nice very glossary that’s now set up in the Guide Section.
The Glossary Guide to end all Guides is the FAA’s Pilot/Controller Glossary. It’s referenced extensively in the FAA’s top-tier handbook to flying The Aeronautical Information Manual (AIM).
The only problem with the Pilot/Controller Glossary is that it’s available only in PDF format and a search in the PDF does not distinguish between the definition entry for a term, acronym, or abbreviation versus simply loose usages of the term in passing. One way that I found to selectively focus in on the FAA definition of many, but not all, acronyms or abbreviations is to put the acronym or abbreviation in parentheses when searching the FAA Pilot/Controller Glossary as the authors of that tome often put the acronym in parentheses after the full wording of the term when giving the definition, e.g., HEIGHT ABOVE AIRPORT (HAA).