For words that only have 3 letters, there's no 4th letter. One example is with the word “incorporate”, there are no extra letters afterwards and so need to be the word "include". The word “addict” is in the BIP39 wordlist however, you might have utilized “addi” for “addict”. In this https://bookmarkworm.com/story18865939/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-seed-phrase-mnemonics-generator