Bip-39 https://www.giantbomb.com/profile/blathayqvn/ Implementations like SLIP39 lengthen BIP39's capabilities by splitting seed phrases into multiple shares, requiring a predefined threshold of shares to reconstruct the first seed. This tactic boosts stability by reducing solitary points of failure. For words that only have three letters, there isn't a 4th letter. One example https://files.fm/u/2eemhhak2q#design