For words that only have 3 letters, there isn't a 4th letter. One example is with the word “incorporate”, there aren't any additional letters afterwards and therefore should be the word "increase". The word “addict” is from the BIP39 wordlist but you might have used “addi” for “addict”. bip39-phrase.com is https://bookmarksurl.com/story4392130/the-basic-principles-of-bip39-passphrase-generator