For words that have only three letters, there isn't a 4th letter. One example is with the word “insert”, there aren't any a lot more letters Later on and thus have to be the word "include". The word “addict” is within the BIP39 wordlist however, you would have made use https://thebookpage.com/story4206591/an-unbiased-view-of-bip39-seed-phrase-github