Bip39 2048 words https://rentry.co/p68weyby Although it uses BIP32 strategy you may nevertheless import BIP39 seeds into Electrum wallet. Also apart from BIp32 There is certainly BIP44 version which some wallet use for that generation of seeds. For words that only have three letters, there isn't a 4th letter. One example https://allyourbookmarks.com/story20421593/bip39-bitcoin-core-not-known-details-about-bip39-generator-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw