For words that have only 3 letters, there isn't a 4th letter. As an example with the word “add”, there won't be any a lot more letters afterwards and so has to be the word "include". The word “addict” is from the BIP39 wordlist but you would've utilised “addi” for https://johsocial.com/story9283869/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool