For words that have only 3 letters, there isn't any 4th letter. For example with the word “add”, there won't be any a lot more letters Later on and therefore must be the word "insert". The word “addict” is within the BIP39 wordlist however , you might have made use https://bookmarkspedia.com/story4358772/not-known-factual-statements-about-bip39-explained