Bip39 Checksum. The passphrase is not really selected within the predefined list of 2048 words – it may be any word or phrase you end up picking. Mnemonics are illustration of entropy. Initial step includes making a choice as to just how much entropy you consider Harmless in your operations. https://tvsocialnews.com/story5042275/bip39-word-list-https-linktr-ee-bip39-a-review-of-bip39-words