Bip39 Dictionary. First of all you must store it SEPARATELY from the seed. Having your seed plus your passphrase in precisely the same place defeats the objective of having a passphrase in the first place. BIP39 specifies a list of 2048 words from which the mnemonic phrase is decided on. https://socialrator.com/story9326000/bip-39-https-linktr-ee-bip39-not-known-factual-statements-about-ian-coleman-bip39