For words that only have 3 letters, there is no 4th letter. One example is with the word “increase”, there aren't any a lot more letters Later on and therefore has to be the word "include". The word “addict” is during the BIP39 wordlist however, you would have made use https://sound-social.com/story9619572/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator