For words that have only 3 letters, there is not any 4th letter. One example is with the word “include”, there isn't any a lot more letters afterwards and so need to be the word "insert". The word “addict” is during the BIP39 wordlist however, you would have made use https://bookmarkspedia.com/story4410447/the-5-second-trick-for-ledger-seed-phrase-bip39