For words that only have 3 letters, there's no 4th letter. By way of example with the word “add”, there are no more letters afterwards and so must be the word "add". The word “addict” is in the BIP39 wordlist however you might have used “addi” for “addict”. Art can https://social-galaxy.com/story4241039/the-invalid-bip39-phrase-diaries