For words that have only 3 letters, there is not any 4th letter. By way of example with the word “incorporate”, there won't be any additional letters afterwards and thus has to be the word "include". The word “addict” is from the BIP39 wordlist but you would've used “addi” for https://bookmarkingace.com/story18815355/little-known-facts-about-bip39-words