For words that only have 3 letters, there is not any 4th letter. One example is with the word “include”, there isn't any far more letters Later on and so needs to be the word "incorporate". The word “addict” is in the BIP39 wordlist however, you would have utilized “addi” https://captainbookmark.com/story18860790/the-invalid-bip39-phrase-diaries