For words that only have three letters, there is absolutely no 4th letter. Such as with the word “incorporate”, there isn't any additional letters afterwards and so need to be the word "include". The word “addict” is during the BIP39 wordlist however , you would have applied “addi” for “addict”. https://bookmarkspecial.com/story18981823/the-5-second-trick-for-ledger-seed-phrase-bip39