Bip39 Checksum. As the 24th is often a checksum word, a list of eight valid candidate words are calculated using the Python script 24thword.py. For words that have only 3 letters, there isn't a 4th letter. For instance While using the word “include”, there won't be any much more letters https://sparedirectory.com/listings577244/bip39-word-list-numbers-https-linktr-ee-bip39-the-5-second-trick-for-bip39-seed-generator