For words that have only three letters, there's no 4th letter. Such as with the word “include”, there won't be any a lot more letters afterwards and so needs to be the word "insert". The word “addict” is while in the BIP39 wordlist however, you might have used “addi” for https://bookmarketmaven.com/story19534461/5-essential-elements-for-bip39-explained