Bip39. Improved protection: By storing your keys offline, hardware wallets secure from online hacks and malware. For words that have only 3 letters, there isn't any 4th letter. As an example With all the word “increase”, there aren't any much more letters afterwards and therefore must be the word "incorporate". https://lombok-directory.com/listings13050178/bip39-tool-https-linktr-ee-bip39-examine-this-report-on-bip39-list