For words that only have three letters, there isn't a 4th letter. One example is with the word “incorporate”, there are no additional letters afterwards and so need to be the word "include". The word “addict” is in the BIP39 wordlist however, you would have applied “addi” for “addict”. If https://prbookmarkingwebsites.com/story21988378/the-fact-about-valid-bip39-seed-phrase-that-no-one-is-suggesting