For words that have only three letters, there isn't any 4th letter. As an example with the word “include”, there are no a lot more letters afterwards and so needs to be the word "insert". The word “addict” is inside the BIP39 wordlist however , you might have employed “addi” https://prbookmarkingwebsites.com/story21863939/little-known-facts-about-bip39-words