For words that have only three letters, there is not any 4th letter. By way of example with the word “insert”, there won't be any more letters afterwards and thus need to be the word "add". The word “addict” is within the BIP39 wordlist however, you would've employed “addi” for https://atozbookmarkc.com/story19815486/little-known-facts-about-bip39-seed-phrase-list