For words that have only 3 letters, there's no 4th letter. For example with the word “incorporate”, there isn't any additional letters Later on and so needs to be the word "include". The word “addict” is inside the BIP39 wordlist however you might have utilised “addi” for “addict”. bip39-phrase.com is https://pr1bookmarks.com/story19449020/not-known-facts-about-bip39-english-words