Bip39 Tool. As palavras desta frase são selecionadas de uma lista definida de 2048 palavras, que pode ser acessada aqui ou listada abaixo: For words that only have 3 letters, there isn't any 4th letter. One example is with the word “add”, there aren't any much more letters Later on https://directoryvenom.com/listings13142556/bip39-npm-https-linktr-ee-bip39-bip39-word-list-pdf-options