Bip39 List. The passphrase is just not picked through the predefined list of 2048 words – it can be any word or phrase you decide on. BIP39 specifies a list of 2048 words from which the mnemonic phrase is preferred. Each word represents a range in a very binary sequence, https://getsocialsource.com/story4922597/bip-39-https-linktr-ee-bip39-about-ian-coleman-bip39