Conference organizing work frequently has me proofreading numerous documents, including a CFP that uses the word “Italianicity.” One Google search later, and rather than depending on Urban Dictionary, this database from Rice University appears as a top search result for all definitions that you need for compound words, portmanteaus, and whatever other wordplay you can’t define.
The Rice University Neologism Database includes entries–some familiar, some surprising–for B-dubs, H.A.M., kaiju, vachaos, and of course l33t. Etymologies are included, some drawing from verified sources, others less verifiable and more reliant on firsthand experience, yet still identifying newer terminology that many dictionaries may not have yet incorporated.
Enjoy tracking the evolution of the English language–just be aware that some of the language may be a bit coarse, some quite disturbing given the levels of hate (based on, to name a few, race, religion, and gender) we have seen produced through language, especially in online discourse. Even though this is a database hosted by a university, you may receive odd glances from people reading over your shoulder.