For words that have only 3 letters, there isn't a 4th letter. One example is with the word “incorporate”, there isn't any more letters afterwards and therefore should be the word "add". The word “addict” is within the BIP39 wordlist however, you would've utilised “addi” for “addict”. Keep your phrase https://bookmarkfly.com/story18827115/the-2-minute-rule-for-bip39-all-words