For words that only have 3 letters, there's no 4th letter. By way of example with the word “include”, there isn't any much more letters afterwards and thus must be the word "include". The word “addict” is from the BIP39 wordlist however, you would have utilised “addi” for “addict”. Many https://ariabookmarks.com/story5345429/the-invalid-bip39-phrase-diaries