For words that only have 3 letters, there isn't a 4th letter. By way of example with the word “insert”, there isn't any more letters afterwards and thus needs to be the word "add". The word “addict” is while in the BIP39 wordlist however you might have utilised “addi” for http://collinmmss433.lucialpiazzale.com/opening-the-power-of-bip39-a-comprehensive-check-out-word-lists-and-secure-pocketbooks