Anything that makes reading comprehension easier is fair game. The list includes not just general vocabulary, but also foods, places, people, fashions, animals, etc. Since ajvocab.com is intended for the "average Joe" there are certain terms we ignore/include:

• We skip most high school vocabulary words, but there is some overlap. In the next few months the plan is to release a list of "core vocab" words that are frequently encountered in literature; words which every English speaker should know—and many of these are high school vocabulary words.
• The 50 US states and major US cities are not covered.
• Common, modern, American idioms and slang are not covered.
• Major countries are not defined, it is assumed they are known. There are other resources if you need to brush up.
• Familiar city names, such as Stockholm and Liverpool, are often included because, although everyone knows that these cities are in Sweden and England respectively, they often do not know exactly where (actually Raphael Andres' awesome photo of Stockholm is reason enough to include the definition for that city).
• Vocabulary for British words, slang, idioms, and geography is extensively covered (we were both baffled when we first encountered the word sleeper as used in Tolstoy's Anna Karenina).
• Our vocabulary collections also cover some French, Latin, and occasionally other languages. Note that it was especially common in the eighteenth century for authors to pepper their novels with Latin and French—so it helps to know at least some.

We skip familiar definitions known by a majority of English speakers. For example, since we consider the words meet, souse, and sleeper elementary vocabulary, books using these words only in the everyday sense are skipped:

• skipped:
  Bob failed to meet us because he is a heavy sleeper when he is soused.
• included:
  It would be meeter for Bob to eat souse on sleepers when trains are not coming.

Rather than making our job easier, this is a major hurdle in completing the vocabulary collections; we must verify not only whether the word is used in the book, but also what sense it is used. The confounded words are the bane of this site's existence.

This sometimes occurs with words of Russian, Hebrew and Arabic origin. Technically they should go on a separate field, but there are already too many fields so we decided to paste them in with the synonyms. Sorry if it bothers you, but unless we have a compelling reason to change it, we won't.

We are working on it—and we need help. Unfortunately we lack the programming infrastructure for such sharing, but if we get enough feedback from people willing to help with word pronunciation we will write the code.

This would basically involve a (non-automated) new user screen, a record button, a playback button, an upload button, and some code infrastructure. It is doubtful we could support smartphones. As with all software, bug fixes and improvements would be incremental.

Shoot us an email on the contact page if you are willing to help with word pronunciations (also note languages and region). If there is enough interest we will write the code.

The icons on the vocabulary page change to reflect the category. So there are special sets of icons for, i.e. places, artists, birds, and music. Not every category has a special set of icons.