Bip39 Wallet. The passphrase just isn't chosen within the predefined list of 2048 words – it could be any word or phrase you select. BIP39 is really a structure implementation that lays out how copyright wallets generate the list of words (or "mnemonic codes") which make up a mnemonic sentence, https://thebookpage.com/story4127946/bip39-passphrase-https-linktr-ee-bip39-getting-my-bip39-wallets-to-work