For words that only have 3 letters, there isn't a 4th letter. By way of example with the word “include”, there aren't any far more letters Later on and so needs to be the word "add". The word “addict” is while in the BIP39 wordlist but you would have employed https://natural-bookmark.com/story19111241/new-step-by-step-map-for-bip39-english-words