For words that have only three letters, there's no 4th letter. As an example with the word “include”, there isn't any far more letters Later on and thus should be the word "include". The word “addict” is inside the BIP39 wordlist however, you might have utilized “addi” for “addict”. Standard https://bookmark-master.com/story18887475/bip39-seed-phrase-fundamentals-explained