For words that have only three letters, there isn't a 4th letter. One example is with the word “include”, there isn't any additional letters Later on and therefore should be the word "include". The word “addict” is from the BIP39 wordlist however you would've utilised “addi” for “addict”. In this https://bookmarkyourpage.com/story4185065/the-greatest-guide-to-seed-phrase-bip39