For words that only have 3 letters, there is no 4th letter. Such as 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”. Obtaining https://doctorbookmark.com/story18954159/a-review-of-bip39-phrase-list