For words that have only three letters, there isn't any 4th letter. Such as with the word “include”, there won't be any more letters Later on and so needs to be the word "include". The word “addict” is in the BIP39 wordlist however you would have made use of “addi” https://opensocialfactory.com/story19711645/the-5-second-trick-for-ledger-seed-phrase-bip39