For words that have only 3 letters, there isn't any 4th letter. For instance with the word “add”, there are no additional letters Later on and therefore should be the word "insert". The word “addict” is in the BIP39 wordlist however, you might have utilized “addi” for “addict”. Artwork is https://bookmark-dofollow.com/story22183138/facts-about-bip39-seed-phrase-github-revealed