For words that have only three letters, there isn't any 4th letter. For instance with the word “incorporate”, there won't be any extra letters afterwards and therefore should be the word "add". The word “addict” is within the BIP39 wordlist however you would've utilized “addi” for “addict”. This extra complexity https://ledbookmark.com/story5287849/the-basic-principles-of-bip39-passphrase-generator