For words that have only 3 letters, there is no 4th letter. By way of example with the word “incorporate”, there isn't any a lot more letters afterwards and so need to be the word "add". The word “addict” is inside the BIP39 wordlist however you would have utilized “addi” https://dailybookmarkhit.com/story19537625/not-known-facts-about-bip39-english-words