For words that have only 3 letters, there's no 4th letter. By way of example with the word “incorporate”, there aren't any a lot more letters Later on and therefore have to be the word "include". The word “addict” is within the BIP39 wordlist however , you would've used “addi” https://bookmarketmaven.com/story19575599/the-definitive-guide-to-bip39-seed-phrase