For words that only have 3 letters, there isn't any 4th letter. One example is with the word “add”, there won't be any far more letters Later on and therefore has to be the word "insert". The word “addict” is while in the BIP39 wordlist however , you might have https://thesocialvibes.com/story4977484/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting