How this word list was built

The list targets the vocabulary of the ISEE and SSAT upper-level verbal sections. Candidate words were checked against word-frequency data (how often a word appears in written English) and judged for grade level, so the list leaves out words most upper-level students already know and words too rare to be worth the time. Each word has a difficulty rating, which the app’s level test and daily workouts use. The ratings are estimates.

Each word’s definition, synonyms, antonyms, example sentences and etymology were written by an AI model and then reviewed by a separate model. Entries it flagged were repaired, and words that could not be fixed were taken out of the list.

A word is listed under a root only when its history says it comes from that root, never because it happens to contain the same letters. Bizarre is not from bi-, and dubious is not from bio; look-alikes like these are shown as “false friends”, with the reason. Each breakdown was checked by a model from a different family than the one that wrote it. When a derivation could not be confirmed, the word was left out rather than guessed.

Each passage was written by AI to use a set of target words naturally, and checked three ways: every word must be used in the sense its definition gives, the prose must read as a real passage rather than a word list, and a separate model answers its questions without the key. Any disagreement sends the passage back for repair. The passages are original practice texts. Where one is set in the past, its people and details may be invented, so do not cite it as a historical source.

Each word, word part and passage page shows the meaning, example sentences and etymology. The answers to the quiz questions stay in the app.

The exams’ practice questions have their own page: how our questions are written and checked.

Errors can remain, and a wrong etymology is exactly the kind we most want to hear about. Write to [email protected] with the page address. A confirmed mistake is fixed in the word list itself, so the fix reaches these pages and the app alike.