For words that have only three letters, there is absolutely no 4th letter. By way of example with the word “increase”, there aren't any additional letters Later on and so need to be the word "insert". The word “addict” is inside the BIP39 wordlist however, you would have made use https://geilebookmarks.com/story18742204/the-5-second-trick-for-ledger-seed-phrase-bip39