For words that only have 3 letters, there's no 4th letter. For instance with the word “include”, there isn't any much more letters afterwards and therefore needs to be the word "insert". The word “addict” is while in the BIP39 wordlist however, you might have employed “addi” for “addict”. Another https://webcastlist.com/story19966885/new-step-by-step-map-for-bip39-english-words