For words that only have three letters, there is absolutely no 4th letter. By way of example with the word “incorporate”, there aren't any additional letters afterwards and so need to be the word "include". The word “addict” is within the BIP39 wordlist however , you might have made use https://socialwoot.com/story20508355/detailed-notes-on-copyright-wallet-seed-phrase-out-of-bip39