For words that only have 3 letters, there is no 4th letter. As an example with the word “include”, there are no far more letters afterwards and thus has to be the word "increase". The word “addict” is in the BIP39 wordlist however , you might have used “addi” for https://ilovebookmark.com/story18926940/the-basic-principles-of-bip39-passphrase-generator