Bip39 Mnemonic Phrase Some words are shorter than 4 letters, including the word “act”. Other words are lengthier than four letters, for instance “summary”. A person list of mnemonic can be used to build various addresses. This process of generating account was released in BIP32 & BIP39 long time back. https://thefairlist.com/story8669151/gen-seed-seed-phrase-generator-an-overview