For words that only have three letters, there's no 4th letter. For instance with the word “include”, there are no extra letters afterwards and so must be the word "add". The word “addict” is during the BIP39 wordlist however you might have applied “addi” for “addict”. This extra complexity improves https://1001bookmarks.com/story18707019/considerations-to-know-about-bip39-word-list-pdf