For words that only have three letters, there is no 4th letter. For instance with the word “incorporate”, there aren't any a lot more letters Later on and thus has to be the word "incorporate". The word “addict” is inside the BIP39 wordlist however you would have employed “addi” for https://bookmarksurl.com/story4270131/the-2-minute-rule-for-bip39-all-words