For words that have only three letters, there is absolutely no 4th letter. For instance with the word “add”, there won't be any a lot more letters afterwards and so must be the word "include". The word “addict” is in the BIP39 wordlist however , you would've utilised “addi” for https://www.creativelive.com/student/chris-mccarthy-26?via=accounts-freeform_2