For words that have only three letters, there isn't any 4th letter. Such as with the word “incorporate”, there are no a lot more letters afterwards and thus needs to be the word "insert". The word “addict” is from the BIP39 wordlist however you would've applied “addi” for “addict”. You https://bookmarkstime.com/story19218602/the-basic-principles-of-bip39-passphrase-generator