Bip39 Mnemonic. First and foremost you ought to store it Independently from a seed. Owning your seed and your passphrase in exactly the same spot defeats the goal of possessing a passphrase to start with. BIP39 specifies a list of 2048 words from which the mnemonic phrase is picked out. https://allkindsofsocial.com/story4906934/bip39-word-list-https-linktr-ee-bip39-bip39-words-fundamentals-explained