For words that have only 3 letters, there isn't any 4th letter. For example with the word “incorporate”, there won't be any far more letters afterwards and thus have to be the word "insert". The word “addict” is from the BIP39 wordlist however , you might have applied “addi” for https://bookmarkprobe.com/story19092744/the-basic-principles-of-bip39-passphrase-generator