For words that have only 3 letters, there is absolutely no 4th letter. One example is with the word “include”, there isn't any a lot more letters Later on and so has to be the word "increase". The word “addict” is during the BIP39 wordlist however , you would have https://bookmarkyourpage.com/story5033009/an-unbiased-view-of-bip39-seed-phrase-github