For words that only have three letters, there isn't a 4th letter. One example is with the word “insert”, there are no extra letters afterwards and so should be the word "incorporate". The word “addict” is within the BIP39 wordlist however you would've employed “addi” for “addict”. Artwork is often https://hylistings.com/story19936726/facts-about-bip39-seed-phrase-word-list-revealed