For words that only have three letters, there is not any 4th letter. Such as with the word “include”, there won't be any a lot more letters Later on and so needs to be the word "include". The word “addict” is inside the BIP39 wordlist but you would have utilised http://andersonsaeu988.iamarrows.com/from-mnemonics-to-safety-and-security-recognizing-bip39-passphrases-and-their-significance-in-copyright