For words that only have 3 letters, there is absolutely no 4th letter. For example with the word “incorporate”, there isn't any a lot more letters Later on and therefore must be the word "increase". The word “addict” is while in the BIP39 wordlist however you would've used “addi” for https://networkbookmarks.com/story18836263/a-review-of-bip39-passphrase