For words that only have three letters, there's no 4th letter. By way of example with the word “increase”, there isn't any far more letters afterwards and therefore need to be the word "include". The word “addict” is during the BIP39 wordlist however, you might have made use of “addi” https://classifylist.com/story21440235/examine-this-report-on-bip39-passphrase