For words that only have 3 letters, there isn't a 4th letter. One example is with the word “add”, there are no extra letters Later on and thus should be the word "incorporate". The word “addict” is inside the BIP39 wordlist however, you would've used “addi” for “addict”. By subsequent https://squareblogs.net/edelinepge/h1-b-recognizing-bip39-a-comprehensive-overview-to-mnemonic-expressions-and