For words that only have three letters, there is not any 4th letter. One example is with the word “incorporate”, there won't be any a lot more letters Later on and therefore should be the word "include". The word “addict” is during the BIP39 wordlist however, you would have used https://bookmarksknot.com/story20518873/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator