For words that have only three letters, there isn't a 4th letter. One example is with the word “add”, there won't be any more letters afterwards and so need to be the word "add". The word “addict” is while in the BIP39 wordlist however you might have utilized “addi” for https://thesocialdelight.com/story4489898/examine-this-report-on-bip39-passphrase