Bip39 Mnemonic. The passphrase just isn't selected in the predefined list of 2048 words – it can be any word or phrase you decide on. BIP39 is actually a design implementation that lays out how copyright wallets build the set of words (or "mnemonic codes") which make up a mnemonic https://monobookmarks.com/story18988682/bip39-https-linktr-ee-bip39-a-review-of-bip39-generator