For words that have only 3 letters, there isn't a 4th letter. As an example with the word “include”, there aren't any far more letters afterwards and so have to be the word "include". The word “addict” is while in the BIP39 wordlist however you would've applied “addi” for “addict”. https://classifylist.com/story20600471/5-simple-techniques-for-bip39-word-list-pdf