For words that have only 3 letters, there's no 4th letter. As an example with the word “insert”, there aren't any additional letters afterwards and so have to be the word "add". The word “addict” is while in the BIP39 wordlist but you would have utilized “addi” for “addict”. Acquiring https://ztndz.com/story23673994/facts-about-bip39-seed-phrase-github-revealed