For words that have only three letters, there is absolutely no 4th letter. By way of example with the word “include”, there isn't any a lot more letters afterwards and so should be the word "include". The word “addict” is from the BIP39 wordlist however you might have utilised “addi” https://dirstop.com/story21928452/bip39-phrase-generator-can-be-fun-for-anyone