Tea's word list is mostly the Webster's 1913 and Century Dictionary long tail, scraped into a flat file over a century after it was typed out via typewriter. We ran a definition lookup over every word and 69,325 words came back with nothing.
Search all 25 lists at once. These are words tea accepts, not words anyone has played.
10 lists · 8,332 words · 12.0% of everything with no definition
12 lists · 58,713 words · 84.7% of everything with no definition
3 lists · 3,058 words · 3.3% of everything with no definition
Not written for a game, or for this century.
Tea runs off a single file. 370,861 words on one line, all lowercase, letters only. It was not made for this game, or for any game.
The list has a name: the Moby Project list. It's public domain, it's been kicking around Unix systems since the 90s, and it's still the default dictionary on most Linux machines, sitting at /usr/share/dict/words. If you're on Linux you can open it right now. 99.7% of Tea's words are in there.
Tea's copy is that same list with everything that isn't a letter taken out. Capitals were lowercased. Hyphens, apostrophes and full stops were deleted rather than swapped for a space, so the letters either side closed up. marble-hearted became marblehearted. this'll became thisll. Aaronite became aaronite. That accounts for most of the words here that look like mistakes. Nothing was misspelled, the punctuation just went.
Under all that it's a 19th century unabridged dictionary, so the vocabulary is old and enormous. Obsolete English, Scots dialect, Victorian chemistry and zoology, and a very long tail of derived forms. Take un: 16,901 words in the file are un on the front of another word that is also in the file. non accounts for 7,299 more, and 12,727 are a word with ly on the end. All real headwords once. Nothing modern lists them, which is why 69,325 of Tea's words come back with no definition.
About 760 words didn't come from the dictionary at all. Somebody added them to the game by hand (yeet, adulting, looksmaxx, obamacare) and they sit in a clump at the front of the file, ahead of the sorted part. ,manual has the full list.