For words that only have three letters, there isn't a 4th letter. As an example with the word “include”, there are no additional letters afterwards and therefore has to be the word "incorporate". The word “addict” is in the BIP39 wordlist however , you would've applied “addi” for “addict”. If https://bookmark-search.com/story18709309/top-guidelines-of-bip39-word-list-pdf