For words that only have three letters, there isn't a 4th letter. For instance with the word “add”, there are no extra letters Later on and therefore need to be the word "increase". The word “addict” is during the BIP39 wordlist however you would've employed “addi” for “addict”. Yet another https://todaybookmarks.com/story19033706/5-simple-techniques-for-bip39-word-list-pdf