For words that have only three letters, there isn't any 4th letter. One example is with the word “incorporate”, there are no extra letters afterwards and so need to be the word "insert". The word “addict” is while in the BIP39 wordlist however , you might have used “addi” for https://www.animenewsnetwork.com/bbs/phpBB2/profile.php?mode=viewprofile&u=1025088