For words that only have three letters, there isn't any 4th letter. For example with the word “add”, there are no far more letters Later on and therefore need to be the word "include". The word “addict” is in the BIP39 wordlist however , you would have employed “addi” for https://bookmarkspiral.com/story18982439/new-step-by-step-map-for-bip39-english-words